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Usage Guide for Sun StorEdge Availability Suite 3.2 Remote Mirror

1. Using the Remote Mirror Replication with Oracle You can use the Oracle standby database for disaster recovery purposes The standby database is maintained by applying the archive redo logs generated at the production database to the standby database With Oracle the database can automatically ship archive logs from primary to standby and can apply the archive logs However the standby database cannot guarantee no loss of committed transactions the current online log file information is lost in the standby database Replicating Online Logs Using online logs replication the remote mirror software mirrors the log files from the primary site to the secondary site If a disaster occurs at the primary site or a network failure occurs the mirrored online redo logs can be used to recover the standby database to the last committed transaction In sync mode potential data loss can be reduced in the event of a disaster In async mode data loss might occur in the event of a disaster The advantages of online logs replication are reduced cost and improved performance Site A Site B with remote mirror with remote mirror Data files and Data files and control files control files Online logs Online logs Archive ji J Archive FIGURE 1 7 Replicating Online logs for the Oracle Standby Database 22 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Full Database Replication
2. In asynchronous mode a write operation is confirmed as complete before the remote volume has been updated Asynchronous replication allows the remote mirror software to return to the host as soon as the write has been completed on the primary volume and been placed on a per volume queue for the secondary site Subsequently the secondary site receives the queued requests in the order that they were queued Once the I O has been completed at the secondary site and the bitmap has been updated to reflect the volume state notification is sent to the primary The advantage of asynchronous replication is that it provides faster response time to the application as long as the asynchronous queue is not full Once the queue is full the subsequent data update of that volume waits to enter the queue and this asynchronous replication might essentially become synchronous operation A disadvantage is that data loss might occur at the secondary site after primary site or network failures The user should size and tune the asynchronous queue size to get optimal operation The default queue size is 16384 data blocks approximately 8 Mbytes To size the queue you can Compute the queue drain rate using dsstat m sndr command Monitor the queue using the kstat sndr command a Discover the I O pattern Also put the remote mirror volumes into logging mode during batch writes like import SQL Load and so on as these operations might fill the queue faster
3. This recovery scenario describes copying files from Site B to Site A and restore the sites to their original roles After the failover is activated Site B is used for the production database To fail over to Site B execute the failover steps described in Failing Over to Site B on page 46 After the network or Site A failure problem is fixed these steps describe how to switch back to Site A as the production database and return Site B as the standby or replicated database v To Shut Down the Site A Database 1 At Site A shut down the database if it is running by using one of the following Oracle commands shutdown immediate or shutdown transactional 2 If you have been replicating only the log files remove the old archive log files using the rm 1M command 3 If you are replicating a file system run the sck 1M command for the replicated volumes before mounting them fsck dev vx rdsk diskgroup volume mount mount point Chapter 3 Failover Scenarios 49 v Resynchronize Files from Site B 1 Copy the control file to Site A alter database backup control file to filename 2 If a cold backup is needed shut down the database and take a cold backup of the database If it is not needed skip to Step 3 shutdown immediate or shutdown transactional perform the cold back up 3 If a cold backup is not needed place the tablespaces into Hot Backup mode
4. Using the remote mirror software you can define multiple volume sets each containing information such as index data rollback and log files If a disaster occurs at the primary site you can accomplish the failover operation to the secondary site quickly to minimize the crash recovery time Consider performance issues carefully when replicating the entire database in sync mode You might use a combination of sync and async modes to replicate depending on the activity and the importance of the files Make sure that if you place volume sets in an I O group all volume sets have the same replication mode do not mix modes in an I O group In sync mode potential data loss can be reduced in the event of a disaster In async mode data loss might occur in the event of a disaster The advantage of full database replication is that the failover operation is relatively straightforward The disadvantages are performance degradation costlier operation and that any primary data corruption is propagated to the secondary volumes Site A Site B with remote mirror with remote mirror Data files and Data files and control files control files Online logs Online logs Archive _ a p Archive FIGURE 1 8 Replicating the Full Oracle Database Chapter 1 Introduction to the Remote Mirror Software 23 24 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December CHAPTER 2 Confi
5. To Start the Database at Site A At Site A start the database in the nomount state startup pfile path initsid ora nomount Open it as a standby database alter database mount standby database Recover the database a If you use managed recovery type recover managed standby database b If you use automatic recovery type the following after the archive logs are shipped alter database recover automatic standby database Chapter 3 Failover Scenarios 61 Swapping Host Roles Restoring Using a Backup Copy and Archive Logs Note This recovery scenario fails Site A over to Site B Site B then becomes the primary remote mirror host and Site A becomes the secondary remote mirror host The Site A database is restored by using a backup copy taken before the failure The archive logs from Site B are then copied to Site A After the failover is activated Site B is used for the production database To fail over to Site B execute the failover steps described in Failing Over to Site B on page 46 After the network or Site A failure problem is fixed these steps describe how to reverse the roles of the sites by restoring a Site A backup copy taken before the disaster After restoring the backup copy the database is updated by using the archive logs shipped from Site B In this scenario you must edit the configuration files for both hosts Configuration File Us
6. alter tablespace tablespacename begin backup 4 Perform one of the following steps a If only log files are being replicated copy the data files to Site A b If the full database is being replicated perform the reverse synchronization also known as resilvering for data file volumes only Make sure that your configuration file specified by config file contains the correct volumes Note Perform the following command at Site A sndradm un f config file 5 If a backup operation was performed in Hot Backup mode end the backup mode alter tablespace tablespacename end backup 50 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Shut down the database shutdown transactional or shutdown immediate If a file system is being replicated unmount all the remote mirror volumes umount mount point Note If you are replicating only online logs perform the following steps At Site A create a standby control file and set the archive destination alter database create standby control file alter system archive log current alter system set log archive dest state 2 enable alter system set log archive min succeed dest 2 At Site A copy the standby control file to Site B To Reverse Synchronize Site A Full Database Replication If you are replicating t
7. December c Edit the etc system file and add the following set shmsys shminfo_shmmax 4294967295 set shmsys shminfo_shmmin 1 set shmsys shminfo_shmmni 100 set shmsys shminfo shmseg 10 set semsys seminfo_semmns 200 set semsys seminfo_semmni 100 set semsys seminfo_semms1 100 set semsys seminfo semopm 100 set semsys seminfo_semvmx 32767 Reboot the system Login as the oracle user Insert the Oracle Universal Installer CD in the CD ROM drive and follow the instructions Note Do not install the Oracle binaries on the replicating volume The software must be installed separately on each system Creating the starter database is optional Do so if required Create the database See the Oracle documentation for creating the database Configuring the Oracle Database Refer to the Oracle documentation for information about installing the Oracle server and the steps to configure the Oracle database See the white paper Guidelines for Using Remote Mirroring Storage Systems for Oracle System for information on planning for the remote mirroring of an Oracle database Use similar setups for both Site A and Site B hosts Chapter 2 Configuring The Remote Mirror and Oracle Software 37 Distributing Data for Optimal Performance You must decide whether you want to replicate the full database or only the online redo logs From a performance perspective it is recommended that you perform online re
8. NSCTL data service framework The remote mirror software is configurable on any device that is accessible through the NSCTL data service framework The sndradm CLI is the external user interface used to manage the remote mirror software FIGURE 1 2 shows the relationship between the Storage Volume SV driver the remote mirror software and the rest of the NSCTL data service framework The I O commands targeted to remote mirror volumes are intercepted by the SV driver and routed through the Sun StorEdge I O stack before being passed on to the storage device driver or the volume manager The I O commands originating in user space are intercepted at the top of the Sun StorEdge I O stack The SV driver routes them through the stack and feeds them back to the storage device driver or volume manager at the bottom of the stack Data also flows in the opposite direction from the storage back to user space Because the remote mirror software is located at the top of the stack before the point in time copy software the remote mirror volume sets must be placed in logging mode sndradm 1 before performing point in time enable copy update or reset operations on any volume that is also part of a remote mirror volume set If the volume set is not in logging mode the point in time copy operation fails and the remote mirror software reports that the operation is denied Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with
9. TABLE 2 1 Oracle File Entities and Suggested Replication Mode Oracle File Entities Access Method Replication mode System tablespace and RollBack tablespace Raw volumes Synchronous Control files and archive logs File system Synchronous Log files Raw volumes Synchronous Data files Raw volumes Asynchronous Index files Raw volumes Asynchronous Temp files Raw volumes Asynchronous Application binaries File system Not replicated If the primary host server becomes unavailable the most important files required to bring the secondary site online in a consistent and up to date state are the System and Rollback tablespace the control files and the archive Logs If consistent data index and temp volumes are available then it is possible to place the secondary database into a recent and consistent state With the addition of the log files it is possible to completely update the database The suggested order and priority when resynchronizing the primary host and secondary host sites are 1 System and RollBack tablespace 2 Control files and archive logs Data files E p Index files 5 Temp files Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Keep a copy of the control files on the file system used to store the archive logs so that a single volume resynchronization can update these files instead of resynchronizing an entire volume solely for the purpose of obtaining
10. The Sun StorEdge Availability Suite 3 2 Software Administration and Operations Guide describes how to adjust the queue including how to use the dsstat and kstat commands Chapter 1 Introduction to the Remote Mirror Software 13 Synchronization Modes The remote mirror software synchronizes data in five modes m Full synchronization m Update resynchronization m Reverse full synchronization m Reverse update synchronization m Logging 14 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Full Synchronization Full synchronization starts a full copy operation from the primary volume to the secondary volume It also enables replication concurrently from the primary volume to the secondary volume any new writes to the primary volume are also replicated to the secondary volume After the operation is complete the remote mirror software maintains the normal replicating mode for the volume either synchronous or asynchronous replication Note The volumes can be made identical using other methods not just a full synchronization When network latencies justify it you can perform the initial synchronization of a volume set by backing up a source or primary volume on magnetic tape on one site then restoring the volume from the tape on the other site During the intervening period that is the period between when the backup is completed and the restore is started place
11. 64 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December v To Perform a Full Database Replication and Start the Database Note Perform these steps at Site B 1 Perform a full synchronization from Site B to Site A sndradm mn f etc opt SUNWrdc rdc cf 2 Start the database in open mode using the following Oracle command startup pfile path initsid ora 3 Create a standby control file make the archive log current and enable the secondary destination of the archived logs alter alter alter alter database create standby control file filename system archive log current system set log archive dest state 2 enable system set log archive min succeed dest 2 4 Copy the data files and standby control files to Site A using the cp 1M copy command Continue to To Start the Database at Site A on page 66 Chapter 3 Failover Scenarios 65 v To Start the Database at Site A 1 At Site A start the database in the nomount state startup pfiles path initsid ora nomount 2 Open it as a standby database alter database mount standby database 3 Recover the database a If you use managed recovery type recover managed standby database b If you use automatic recovery type the following after the archive logs are shipped alter database recover automatic standby d
12. AnswerBook2 docs sun com Sun StorEdge Solstice Disk Suite Sun ATM Sun Enterprise Sun Fire and Solaris are trademarks or registered trademarks of Sun Microsystems Inc in the U S and in other countries All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International Inc in the U S and in other countries Products bearing SPARC trademarks are based upon an architecture developed by Sun Microsystems Inc The OPEN LOOK and Sun Graphical User Interface was developed by Sun Microsystems Inc for its users and licensees Sun acknowledges the pioneering efforts of Xerox in researching and developing the concept of visual or graphical user interfaces for the computer industry Sun holds a non exclusive license from Xerox to the Xerox Graphical User Interface which license also covers Sun s licensees who implement OPEN LOOK GUIs and otherwise comply with Sun s written license agreements Use duplication or disclosure by the U S Government is subject to restrictions set forth in the Sun Microsystems Inc license agreements and as provided in DFARS 227 7202 1 a and 227 7202 3 a 1995 DFARS 252 227 7013 c 1 ii Oct 1998 FAR 12 212 a 1995 FAR 52 227 19 or FAR 52 227 14 ALT III as applicable DOCUMENTATION IS PROVIDED AS IS AND ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR
13. NON INFRINGEMENT ARE DISCLAIMED EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLY INVALID Copyright 2002 Sun Microsystems Inc 4150 Network Circle Santa Clara California 95054 Etats Unis Tous droits r serv s Sun Microsystems Inc a les droits de propri t intellectuels relatants la technologie incorpor e dans le produit qui est d crit dans ce document En particulier et sans la limitation ces droits de propriete intellectuels peuvent inclure un ou plus des brevets am ricains num r s a http www sun com patents et un ou les brevets plus suppl mentaires ou les applications de brevet en attente dans les Etats Unis et dans les autres pays Ce produit ou document est prot g par un copyright et distribu avec des licences qui en restreignent l utilisation la copie la distribution et la d compilation Aucune partie de ce produit ou document ne peut tre reproduite sous aucune forme parquelque moyen que ce soit sans l autorisation pr alable et crite de Sun et de ses bailleurs de licence s il y ena Le logiciel d tenu par des tiers et qui comprend la technologie relative aux polices de caract res est prot g par un copyright et licenci par des fournisseurs de Sun Des parties de ce produit pourront tre d riv es des syst mes Berkeley BSD licenci s par l Universit de Californie UNIX est une marque d pos e aux Etats Unis et dans d autres pays et licenci e exclusivement pa
14. Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Reverse Update Synchronization During reverse update synchronization mirroring the remote mirror software compares the bitmaps between the primary and secondary sites and replicates only the changed blocks from the secondary site to the primary site It resynchronizes the primary volume from the secondary volume It updates the primary volume according to the changes based on logs maintained while replication was stopped It also enables concurrent replication between the primary volume and secondary volumes any new write operations to the primary are also replicated to the secondary volumes This remote mirror feature can help reduce application downtime You can use the primary volume during reverse update synchronization The primary volume shows a consistent volume image of the latest data as soon as the reverse update synchronization starts If your application had been writing to the secondary volume as part of a failure or disaster rehearsal you can move the application back to the primary volume when the reverse update synchronization starts FIGURE 1 6 shows a reverse update resynchronization from the secondary system to its primary system 1 The remote mirror software on host1 retrieves the secondary bitmap 1R from host2 for one of the remote mirror software managed volumes affected by the interruption 2 The softwa
15. access to the control files Alternatively you can create an SQL script to generate the control file and copy it to the secondary site Note that any future changes made to the database data files usage also require changes to the remote mirror implementation and the configuration of the secondary host The application binaries are not being replicated in this scenario but could be replicated if required Setting Up the TCP IP Network Link You can use any TCP IP network transport software such as SunATM or Gigabit Ethernet transports This section assumes that one of two types of ATM are installed SunATM 155 or SunATM 622 These interfaces run at theoretical speeds of 155 Mbytes per second and 622 Mbytes per second respectively with realistic throughput of 93 Mbytes per second and 400 Mbytes per second If the two servers in the remote mirror configuration are not on a local network then the limiting factor for throughput is the bandwidth of the ATM link being used See TABLE 2 2 When a volume set is in enabled and replicating mode the remote mirror software uses only a small fraction of the available bandwidth depending on the amount of data being modified on the volume set and the number of sets enabled Running in sync mode potentially requires a wide network pipe so that the network will not be a bottleneck as the I O operation does not complete until it has been written to both the local and the remote servers In async mode a
16. amp Sun microsystems Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracles Databases Sun Microsystems Inc 4150 Network Circle Santa Clara CA 95054 U S A 650 960 1300 December Send comments about this document to docfeedback sun com Copyright 2003 Sun Microsystems Inc 4150 Network Circle Santa Clara California 95054 U S A All rights reserved Sun Microsystems Inc has intellectual property rights relating to Eo ees embodied in the product that is described in this document In particular and without limitation these intellectual property rights may include one or more of the U S patents listed at ttp www sun com patents and one or more additional patents or pending patent applications in the U S and in other countries This document and the product to which it pertains are distributed under licenses restricting their use copying distribution and decompilation No part of the product or of this document may be reproduced in any form by any means without prior written authorization of Sun and its licensors if any Third party software including font technology is copyrighted and licensed from Sun suppliers Parts of the product may be derived from Berkeley BSD systems licensed from the University of California UNIX is a registered trademark in the U S and in other countries exclusively licensed through X Open Company Ltd Sun Sun Microsystems the Sun logo
17. example in the example entry shown in Configuration File Used in This Example on page 62 change atm10 to atm20 and atm20 to atm10 Restore the backup copy taken before the disaster If you are replicating a file system and are replicating online logs only unmount those volumes only umount mount point Chapter 3 Failover Scenarios 63 v To Shut Down Site B and Enable the Remote Mirror Software 1 At Site B shut down the database if it is running by using the following Oracle command shutdown immediate or shutdown transactional 2 Disable the remote mirror software and discard the remote mirror bitmap sndradm dn f etc opt SUNWrdc rdc cf 3 Edit the rdc cf file to swap the Site A primary host information and Site B Edit the rdc cf file to swap the Site A primary host information and Site B secondary host information For example in the example entry shown in Configuration File Used in This Example on page 62 change atm10 to atm20 and atm20 to atm10 4 Enable the remote mirror software sndradm en f etc opt SUNWrdc rdc cf m If you are performing a full database replication perform a full synchronization for the archive log and online log volumes specified in the rdc cf file You might need separate configuration files to specify each volume type Continue to To Perform a Full Database Replication and Start the Database on page 60
18. from its source primary volume However restoration of a failed primary disk might require reverse synchronization using the surviving remote mirror as the source Mode where a bitmap tracks writes to a disk rather than a running log of each I O event This method tracks disk updates that have not been remotely copied while the remote service is interrupted or impaired The blocks that no longer match their remote sets are identified for each source volume The software uses this log to re establish a remote mirror through an optimized update synchronization rather than a complete volume to volume copy The system or volume on which the host application is principally dependent For example this is where the production database is being accessed This data is to be replicated to the secondary by the software 71 Replication Once a volume set has been initially synchronized the software ensures that the primary and secondary volumes contain the same data on an ongoing basis Replication is driven by user layer application write operations replication is an ongoing process Reverse synchronization An operation used during recovery rehearsals Logging keeps track of test updates applied to the secondary system during the rehearsal When the primary is restored the test updates are overwritten with the blocks from the primary image restoring matching remote sets Secondary or remote host or volume The remote counterpart of the primary
19. mode Mixed groups those where mirroring modes are asynchronous for one set and synchronous for another set are not allowed The remote mirror software maintains write ordering for volumes in a group to ensure that the data on the secondary volumes is a consistent copy of the corresponding primary volumes Data can be queued on disk as well as in memory Memory based queues are the default See Disk Based Asynchronous Queues on page 5 Replicate data from one primary volume to a secondary volume the secondary volume then replicates the data again to another secondary volume and so on in a daisy chain fashion See One to Many Many to One and Multihop Volume Sets on page 7 Concurrently transmit to and receive remote dual copies from its remote counterpart Also known as a bilateral relationship Replicate data from one primary volume to many secondary volumes residing on one or more sites When you perform a forward resynchronization you can synchronize one volume set or all volume sets Issue a separate command for each set You can also update the primary volume using a specific secondary volume See One to Many Many to One and Multihop Volume Sets on page 7 Resynchronize volumes following disk link system and storage platform outages you only replicate those blocks that were modified Use RAID volumes as part of your remote mirror software strategy Volumes can be any RAID level Usage Guide for
20. smaller pipe is acceptable as the data is not transmitted in real time During full synchronization operations however the maximum available bandwidth is used since the entire contents of the volumes are transmitted over the link A trade off must be made between the cost of installing and operating multiple lines and the time taken to replicate a set of volumes TABLE 2 2 Speeds for Various Communications Protocols Link Speed OC 1 51 85 Mbytes per second OC 3 155 Mbytes per second OC 12 622Mbytes per second OC 48 2 4 Gbytes per second OC 192 9 6 Gbytes per second Chapter 2 Configuring The Remote Mirror and Oracle Software 29 TABLE 2 2 Speeds for Various Communications Protocols Continued Link Speed T 3 E 3 T 1 45 Mbytes per second theoretical 27 2 Mbytes per second realistic 34 5 Mbytes per second theoretical 21 Mbytes per second realistic 1 54 Mbytes per second theoretical 0 92 Mbytes per second realistic Allocating Volumes Note When selecting a volume to be used in the remote mirror software volume set ensure that volume does not contain disk label private areas for example slice 2 on a Solaris operating environment formatted volume The disk label region is contained in the first sectors of cylinder 0 of a disk The safest method is to ensure that cylinder 0 is not part of any logical volume that is replicated except for volumes under VERITAS Volume Manager control where cylind
21. to Site B if it provides greater availability 1 Calculate the normal time to reboot the server m fail over to Site B switch back to Site A Failing over to Site B requires you to mount the necessary file systems a start recover and roll forward the application a switch users from Site A to Site B Switching back to Site A requires you to perform a reverse synchronization of the remote mirror software volumes multiple times shut down the application on Site B unmount any file systems on Site B Reverse synchronization of the remote mirror volumes to Site A and waiting for completion requires you to 43 44 mount the application volumes on Site A a synchronize the remote mirror volume set Start the application on Site A Identifying and Resolving Failures The remote mirror software can automatically detect network link failures and remote system failures the software can log incomplete and new write operations After restoring the network or remote site you can re enable and resynchronize the volumes If the remote mirror volume sets are running in async mode you should not see any performance degradation occurring on Site A when the link fails However in sync mode any current I O operations to must first time out During this time any application on Site A that has pending I O operations might appear to freeze After a time out has occurred the remote mirror software en
22. usr opt SUNWesm sbin sndradm command details and information see the Sun StorEdge Availability Suite 3 2 Remote Mirror Administration and Operations Guide To Enable and Replicate Volumes Use one of the following commands to enable the volumes defined in your configuration file m sndradm e n f config file a sndradm E n f config file where e indicates that a full resynchronization between volumes is required E clears the bitmap logging to indicate that the specified volumes are fully synchronized and enables logging Typically you use this command if the data at Site B already matches Site A and no replication is required n indicates interactive mode is off that is you do not have to respond to program prompts to enable the volume sets f config file specifies the configuration file Perform the initial replication from Site A to Site B using the sndradm m command The replication command options are Replication type Command Copy the entire contents of the primary volume to the secondary sndradm m volume also known as full synchronization Copy the entire contents of the secondary volume to the primary sndradm m r volume also known as full reverse synchronization Update only the changed data of the primary volume to the sndradm u secondary volume also known as update synchronization or resynchronization Update only the changed data of the secondary volume to the sndradm u r primary
23. volume also known as reverse synchronization or reverse update Chapter 2 Configuring The Remote Mirror and Oracle Software 35 3 For monitoring remote mirror operations use the usr opt SUNWscm sbin scmadm SM or usr opt SUNWscm sbin dsstat commands Installing and Configuring Oracle The following sections describe general guidelines for installing Oracle For detailed instructions see the Oracle installation documentation such as the Installation Guide for Oracle 8 1 7 for the Sun Solaris Operating Environment See Installation Requirements on page 26 for volume manager disk space and memory requirements Note The remote mirror software operates with any version of Oracle In this guide Oracle 8 1 7 is assumed If you are using any version prior to 8 1 ignore the recover managed syntax for managed recovery of the standby database v To Install Oracle 1 Login as the root user 2 Create the orainstall group and attach groupid to it 3 Create user oracle with the main group orainstall and attach userid to it 4 Perform the following steps using admintool 1M a Create the directory opt 1bin and include it in your path b Edit the Oracle user s environment variables for the appropriate login shell scripts for ORACLE HOME ORACLE SID ORACLE TERM LD_LIBRARY_PATH and PATH to include ORACLE HOME 36 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases
24. where data copies are written to and read from Remote copies are transmitted without host intervention between peer servers A server might act as primary storage for some volumes and secondary remote storage for others Synchronization The process of establishing an identical copy of a source disk onto a target disk as a precondition to the software mirroring Synchronous replication Synchronous replication is limited to short distances tens of kilometers because of the detrimental effect of propagation delay on I O response times Update synchronization Update synchronization copies only those disk blocks identified by logging reducing the time to restore remotely mirrored sets Volume set file A text file containing information about specific volume sets This text file is not the same as the Configuration location which contains information about all configured volume sets used by the remote mirror and point in time copy software 72 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December
25. N ADDRESS LIST ADDRESS PROTOCOL IPC KEY sid ADDRESS LIST ADDRESS PROTOCOL TCP HOST Site A hostname PORT 1521 SID_ LIST LISTENER SID LIST SID_DESC GLOBAL DBNAME sid domain name ORACLE HOME oral oracle product 817 SID NAME sid Chapter 2 Configuring The Remote Mirror and Oracle Software 39 40 File tnsnames ora sid domain name DESCRIPTION ADDRESS LIST ADDRESS PROTOCOL TCP HOST Site A hostname PORT 1521 CONNECT DATA SERVICE NAME sid domain name sid domain name DESCRIPTION ADDRESS LIST ADDRESS PROTOCOL TCP HOST Site B hostname PORT 1521 CONNECT DATA SID sid File sqlnet ora NAMES DEFAULT DOMAIN domain name automatic _ipc off Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Site B File listener ora LISTENER DESCRIPTION LIST DESCRIPTION ADDRESS LIST ADDRESS PROTOCOL TCP HOST Site B hostname PORT 1521 SID LIST LISTENER SID LIST SID_DESC GLOBAL DBNAME sid domain name ORACLE HOME oral oracle product 817 SID NAME sid File tnsnames ora sid domain name DESCRIPTION ADDRESS LIST ADDRESS PROTOCOL TCP HOST Site B hostname PORT 1521 CONNECT DATA SERVICE NAME sid dom
26. Oracle Databases December 1 0 i Sun SV nsctl 1 0 i Sun SV yw Remote mirror Remote mirror q Point in time copy SDBC raw volume manager Storage Device drivers sd and ssd Primary host Kernel RPC Point in time copy nsctl SDBC raw volume manager Storage Device drivers sd and ssd Secondary host 1 1 0 commands and data enter and exit the remote mirror software through the Sun StorEdge Storage Volume SV driver software 2 Mediated by nsct1 the data flows through remote mirror software and optionally the point in time copy software and the Storage Device Block Cache SDBC drivers to its destination on the storage array or in user space FIGURE 1 2 The Remote Mirror Software Architecture Chapter 1 Introduction to the Remote Mirror Software 11 Replication Modes The remote mirror software supports two modes of data replication m Synchronous replication a Asynchronous replication The replication mode is a user selectable parameter for each remote mirror volume set Use the sndradm enable command and select the volume set s sync or async parameter Use the sndradm R m command to change the replication mode thereafter The volumes can be updated synchronously in real time or asynchronously using a store and forward technique Typically a primary volume is first explicitly
27. Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December TABLE 1 1 Remote Mirror Software Features Continued This Feature Enables You To Security and Internet Protocols Stop and start control of remote replication on a logical volume basis Point in time copy software integration Synchronous and asynchronous volume replication between physically separate sites Use Version 3 2 securely and efficiently in the Sun Solaris 8 and 9 operating environments which support Internet Security Protocol IPsec The Solaris 8 and 9 operating environments also support Internet Protocol Version 6 IPv6 The Solaris 7 operating environment does not support IPv6 Version 3 2 does not require the use of an rhosts file You place the host machines to be used in the etc hosts file of each host running the remote mirror software in your configuration Have fine control over replication at the logical volume level You can include volumes containing critical data by specifying these volumes as part of a remote mirror software volume set You can also exclude volume with noncritical data from remote mirror software options Make point in time volume copies of your data for additional point in time coordination and recovery Plan for disaster recovery and business continuance using physically separate primary and secondary sites The remote mirror software design is link neutral
28. UNE UTILISATION PARTICULIERE OU A L ABSENCE DE CONTREFA ON oS Adobe PostScript Ory Please Ga j 8 Recycle Contents 1 Introduction to the Remote Mirror Software 1 Why Should You Use Data Replication 2 Oracle and the Sun StorEdge Availability Suite Remote Mirror Software A Solution 2 Overview 3 Features 4 Disk Based Asynchronous Queues 5 6 One to Many Many to One and Multihop Volume Sets 7 Order Dependent Writes and Volume Set Grouping 8 Mutual Backup 9 Architecture 10 Replication Modes 12 Synchronous Replication 12 Asynchronous Replication 13 Synchronization Modes 14 Full Synchronization 15 Update Resynchronization 16 Reverse Full Synchronization 18 Reverse Update Synchronization 19 Logging 20 Using the Remote Mirror Replication with Oracle 22 Replicating Online Logs 22 Full Database Replication 23 2 Configuring The Remote Mirror and Oracle Software 25 Installation Requirements 26 Configuring the Remote Mirror Software 27 Determining Application Replication Requirements 27 Setting Up the TCP IP Network Link 29 Allocating Volumes 30 v To Create and Set Up Volumes 31 About Replicating File Systems 32 Creating a Remote Mirror Volume Set File 32 Bitmap Volume Configuration 34 Enabling and Replicating the Remote Mirror Volumes 35 v To Enable and Replicate Volumes 35 Installing and Configuring Oracle 36 v Tolnstall Oracle 36 Configuring the Oracle Database 37 Distributing Data for Optimal Performance 38 Onlin
29. a remote volume backup to local Site A and also be a direct storage resource for applications on Host B Under these circumstances you can replicate Host B volumes to Site A This reciprocal backup arrangement supported by the remote mirror software is known as mutual backup or dual backup With mutual backup the remote mirror software volumes considered primary by Site B are administered from the Site B session Site B replicated volume devices are considered secondary volumes at Site A In this case you need to configure two unique volume sets for each site For example m Volume set 1 contains primary Site A volumes replicated to secondary Site B m Volume set 2 contains primary Site B volumes replicated to secondary Site A See FIGURE 1 1 host ai aha NOS Site B secondary host Site A Site B applicationt _ ile Site B primary host Site A secondary host p y Site B Site A a application2 secondary volume A1 Replicated to Site A primary volume B1 FIGURE 1 1 Mutual Backup Chapter 1 Introduction to the Remote Mirror Software 9 10 Architecture The remote mirror software operates on logical volumes that can be linear striped or RAID devices You can create the logical volumes by using the Sun Solstice DiskSuite or VERITAS Volume Manager software The core remote mirror software code is a kernel module that interfaces to the network storage control module
30. ain name sid domain name DESCRIPTION ADDRESS LIST ADDRESS PROTOCOL TCP HOST Site A hostname PORT 1521 CONNECT DATA SID NAME sid domain name Chapter 2 Configuring The Remote Mirror and Oracle Software 41 File sqlnet ora NAMES DEFAULT DOMAIN domain name automatic ipc off Implementing the Remote Mirror Software for an Existing Database Use the following steps to implement the remote mirror software for an existing database 1 Make sure no data changes occur to the database at Site A quiesce the application if needed D Determine the requirements for the remote mirror software Allocate storage on Site B for the remote mirror volumes Create the remote mirror configuration files Perform the initial remote mirror replication of volumes Define procedures for normal and failure conditions SL ENT OT Bs Oo Rehearse the procedures 42 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December CHAPTER O Failover Scenarios Determine Procedures Before You Begin Determine when to fail over to Site B If you switch to Site B you have to perform steps both in switching to it and later switching back to Site A Document the time for each step and its related factors so that when a failure occurs you can determine the best approach for the current scenario In summary only switch
31. al Disable the remote mirror software and discard the remote mirror bitmap sndradm dn f etc opt SUNWrdc rdc cf Edit the rdc cf file to swap the Site A primary host information and Site B secondary host information For example in the example entry shown in Volume Set File Used in This Example on page 57 change atm10 to atm20 and atm20 to atm10 Unmount the replicating volume at the mount point If you are replicating a file system and are performing full database replication unmount all remote mirror volumes If you are replicating online logs only unmount those volumes only umount mount point v To Shut Down Site B and Enable the remote mirror Software 1 At Site B shut down the database if it is running by using the following Oracle command shutdown immediate or shutdown transactional Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December 2 Disable the remote mirror software and discard the remote mirror bitmap sndradm dn f etc opt SUNWrdc rdc cf 3 Edit the rdc cf file to swap the Site A primary host information and Site B Edit the rdc cf file to swap the Site A primary host information and Site B secondary host information For example in the example entry shown in Volume Set File Used in This Example on page 57 change atm10 to atm20 and atm20 to atm10 4 Enable
32. an application has multiple logical volumes assigned application data integrity can be maintained by one of the following a Specifying that all remote mirror software volumes associated with that application are in sync mode m Using the Sun StorEdge Availability Suite 3 2 point in time copy software to make periodic recoverable point in time copies If you use point in time copy software the remote point in time snapshot is taken while the application is in the recoverable state For example most database applications allow for a hot backup If a remote point in time copy were made of the entire replicated database while the primary was in hot backup mode then a consistent remote database is available by using the point in time copy and the log files taken while the database was in hot backup mode Note You must place the remote mirror volume set in logging mode for the point in time copy software to successfully perform an enable copy update or reset operation on a remote mirror volume If the volume set is not in logging mode the point in time copy operation fails and the remote mirror software reports that the operation is denied 8 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Mutual Backup Typically volumes are replicated from local Site A to remote Site B However as applications are geographically distributed a storage system at remote Site B can be
33. are starts a full reverse copy operation from the secondary volume to the primary volume It also enables concurrent replication from the primary volume to the secondary volume any new writes to the primary volume are also replicated to the secondary volume This remote mirror feature can help reduce application downtime You can use the primary volume during reverse synchronization The primary volume shows a consistent volume image of the latest data as soon as the reverse synchronization starts If your application had been writing to the secondary volume as part of a failure or disaster rehearsal you can move the application back to the primary volume when the reverse synchronization starts FIGURE 1 5 shows the full reverse synchronization process 1 The data might already be resident in host2 data cache or it might require a secondary disk access If so the remote mirror software on host1 requests blocks from the up to date secondary volume on host2 2 The software on host2 transmits the cache blocks 2R over the link to a software region on host1 with destaging instructions 3 The software on host1 updates its disk Site A Primary Site B Secondary Disk Disk Cache HBA HBA Cache host1 host2 RM le T 3 1 IDE TT y Primary Up to date disk TCP IP secondary disk See 2R FIGURE 1 5 Reverse Full Synchronization 18
34. atabase 66 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Implementing One To Many Replication Note See One to Many Many to One and Multihop Volume Sets on page 7 The concepts and failover scenarios of one to one replication described in this guide and one to many replication are similar One to many replication introduces the concept that you can perform replication in parallel For example consider the following scenario it enables you to test and develop live data at two remote sites a A production database is located in California Site A and is the remote mirror primary host location Its configuration requires one volume set definition each for A test database located in Massachusetts Site B secondary host 1 a A development database located in Florida Site C secondary host 2 The remote mirror configuration would include two entries each with a unique Site A bitmap volume You cannot use the same bitmap at Site A for the Site B and Site C hosts because you would risk data corruption when you synchronize all volume sets If you configure the remote mirror software to operate in this one to many mode the database can be replicated to Site B and Site C simultaneously Also if the network link in Massachusetts has failed the Site A to Site C link is unaffected and remains live and replicating One to many replic
35. ation helps provide many creative replication and disaster recovery solutions For example depending on distance and the network link type you can replicated one volume set in synchronous mode and another in asynchronous mode You could also reverse update volumes from Site B to Site A then replicate the Site A volumes to Site C Chapter 3 Failover Scenarios 67 68 Implementing Multihop Replication Note See One to Many Many to One and Multihop Volume Sets on page 7 The concept difference between one to many and multihop replication is that you can replicate volumes in parallel using one to many multihop replication typically occurs serially This guide describes how to swap host roles Site A becomes the secondary site location for data while Site B becomes the primary site location With one to many replication Site B can be a primary and secondary site location simultaneously exclusive of Oracle database configuration of course Using the site example in Implementing One To Many Replication on page 67 you can replicate volumes from primary Site A to secondary Site B Then primary Site B can replicate to secondary Site C This setup requires you to define two volumes sets for Site B with each volume set containing a unique bitmap volume one for Site A to Site B replication and one for Site B to Site C replication If the Site A volumes become corrupted or unavailable later you can replicate the Site B
36. ce the downtime during outages long outages could be devastating Business also need to reduce the amount of manual intervention required reduce downtime and provide more up to date data in case of an outage While many hardware and software tools provide high reliability on an individual basis a degree of unreliability is introduced when they are integrated into a system Remote mirroring has traditionally been employed in disaster recovery and business continuance strategies to provide redundant storage of critical information across physically separate sites An investment in multiple data copies can be leveraged into new information sharing opportunities across distributed enterprises The result can be operational efficiency for physically disparate computing environments and strategic advantage due to increased information access Oracle and the Sun StorEdge Availability Suite Remote Mirror Software A Solution The Oracle database software is a proven database application for enterprises with large volumes of data The increasing percentage of Oracle installations on UNIX platforms has indirectly triggered a dependency on the UNIX operating environment and data availability Understanding this critical issue Sun Microsystems Inc has developed the Sun StorEdge Availability Suite 3 2 Remote Mirror software for remote replication and mirroring of data The remote mirror software can help businesses to m Replicate data to another site
37. cified by config file contains the correct volumes sndradm u r f config file If you are replicating a file system run the sck 1M command for the replicated archive log volume before mounting it fsck dev vx rdsk diskgroup volume mount mount point Start the database and mount the database startup pfile path initsid ora mount Recover the database alter database recover automatic database Next apply the log files to bring the database to the current level Shut down the databases at Site A and Site B Perform this command from both sites shutdown transactional or shutdown immediate Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December v 1 To Return the Sites to Their Original Roles If a file system is part of the replication unmount the online redo logs volumes umount mount point Perform the reverse update synchronization also known as resilvering Make sure that your configuration file specified by config file contains the correct online logs volumes sndradm un r f config file If you are replicating a file system run the fsck 1M command for the replicated online redo log volume before mounting it fsck dev vx rdsk diskgroup volume mount mount point a Start the database in nomount state s
38. copied to a designated secondary volume to establish matching contents As applications write to the primary volume the software replicates changes to the secondary volume keeping the two volumes consistent In the event of planned or unplanned outages the software maintains per device bitmap volumes that are marked to indicate changed blocks with a granularity of 32 Kbytes per segment This technique optimizes resynchronization by allowing the software to resynchronize only the blocks that have changed since the last synchronization Synchronous Replication In synchronous mode a write operation is not confirmed as complete until the remote volume has been updated Synchronous mirroring forces the remote mirror software to wait until an acknowledgement of the receipt of the data is received from the secondary by the primary before returning to the application The application is not acknowledged until the write at the secondary site is complete The advantages of synchronous replication are that it is more reliable and can help reduce the risk of data loss One disadvantage might be an increase in write response time especially for large data sets or long distance replication where write operations can incur additional latency because of the time required to transfer data and return acknowledgements 12 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Asynchronous Replication
39. do logs replication and use the standby database at the secondary site However you can implement full database replication Online Log File Replication This choice assumes that Site B hosts the standby database If the online redo files are multiplexed use sync mode on all the members and groups If async mode is used data loss might occur during disaster failover operations Full Database Replication Use separate volumes for redo logs system data files data index RBS and archive logs Even though using sync mode for all the volumes helps make failover operations easier it has an impact on performance at the Site A host Sample Oracle Configuration Files You can use these files for both online log replication and full database replication All files are located in the ORACLE HOME network admin directory Any text in italics is a variable that you must supply m Site X hostname name of the host where X is Site A or Site B m sid system identifier a domain name domain for the Site A host Note For ease of use Oracle provides a graphical program to help add information to these files instead of editing them in a text editor The program is named Net8 Assistant and can be started from SORACLE_HOME bin netasst 38 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Site A File listener ora LISTENER DESCRIPTION LIST DESCRIPTIO
40. dures a failover scenario to Site B After you perform these steps Site B is the failover site As soon as Site A is accessible you must perform a switch back or reverse role scenario To switch Site A back as the production database see Switching Back to Site A as the Production Database By Copying Files on page 49 or Switching Back to Site A as the Production Database By Restoring a Backup Copy on page 53 46 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December v To Shut Down the Databases 1 At Site A shut down the production database if it is running by using one of the following Oracle commands shutdown immediate or shutdown abort or shutdown transactional 2 At Site B shut down the standby database if it is running by using one of the following Oracle commands shutdown immediate or shutdown transactional v To Fail Over to Site B Note Perform these steps from Site B 1 Place the remote mirror volumes into logging mode so that changes can be applied to Site A later sndradm ln f config file When you issue this command from Site B the remote host it does not affect volumes that are currently synchronizing Wait until all volumes have finished synchronizing before issuing this command 2 If you are replicating a file system run the fsck 1M command for the replicated volumes before mou
41. e A and designating Site A as the production database host After the failover is activated Site B is used for the production database To fail over to Site B execute the failover steps described in Failing Over to Site B on page 46 After the network or Site A failure problem is fixed these steps describe how to switch back to Site A as the production database and return Site B as the standby or replicated database by restoring a pre failure backup Site A database To Prepare Site A and Site B At Site B create the control file script using the following Oracle commands alter database backup controlfile to trace Note Perform the following procedures at Site A Remove the old archive logs using the rm 1M command Restore the data files and control files from the backup performed before the disaster If only log files are being replicated or if the archive logs are not a remote mirror volume copy the archived log files from Site B using the cp 1M command If you are replicating the full database and the archive logs are in a replicating volume reverse update synchronization of only the archived log file volume a If a file system is part of the replication unmount the archive logs volumes umount mount point Chapter 3 Failover Scenarios 53 54 b Perform the reverse update synchronization also known as resilvering Make sure that your configuration file spe
42. e Log File Replication 38 Full Database Replication 38 Sample Oracle Configuration Files 38 Site A 39 Site B 41 Implementing the Remote Mirror Software for an Existing Database 42 3 Failover Scenarios 43 iv Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Determine Procedures Before You Begin 43 Identifying and Resolving Failures 44 Link Failures 45 v To Manually Place the Remote Mirror Software into Logging Mode 45 v To Resynchronize Site B from Site A 46 Failing Over to Site B 46 v To Shut Down the Databases 47 v To Fail Over to Site B 47 Switching Back to Site A as the Production Database By Copying Files 49 v To Shut Down the Site A Database 49 v Resynchronize Files from Site B 50 v To Reverse Synchronize Site A Full Database Replication 51 Switching Back to Site A as the Production Database By Restoring a Backup Copy 53 v To Prepare Site A and Site B 53 v To Return the Sites to Their Original Roles 55 Swapping Host Roles Database Copy 57 Volume Set File Used in This Example 57 To Shut Down the Site A Database 58 To Shut Down Site B and Enable the remote mirror Software 58 To Perform a Full Database Replication and Start the Database 60 lt lt To Replicate the Online Log Files Only 60 v To Start the Database at Site A 61 Swapping Host Roles Restoring Using a Backup Copy and Archive Logs 62 Configuration File Used in This Example 62 To Shut Down
43. ection The software supports the replication of volumes located on many different hosts to volumes on a single host The terminology differs from the one to many configuration terminology where the one and the many referred to are volumes Multihop replication indicates that the secondary host volume of one volume set acts as the primary host volume of another volume set it is still the secondary volume of the first volume set In the case of one primary host volume A and one secondary host volume B the secondary host volume B appears as primary host volume A1 to the secondary host volume B1 Chapter 1 Introduction to the Remote Mirror Software 7 Order Dependent Writes and Volume Set Grouping Write ordering is maintained for groups of asynchronously replicating volume sets The general definition of write ordering is that write operations directed to the target volume occur in the same order as write operations to the source The group of target volumes is a copy of the group of source volumes This feature can be valuable in those cases where you can avoid application requirements that limit operations For example a database application might limit partition sizes to no greater than 2 Gbytes In this case you might group volume sets to create a virtual large volume that preserves write operations Otherwise you might risk having inconsistent data by trying to update volume sets individually instead of as a group When
44. ed in This Example In this section the example remote mirror configuration file is named etc opt SUNWrdc rdc cf Following is the entry in the rdc cf file showing Site A atm10 and Site B atm20 details See also Creating a Remote Mirror Volume Set File on page 32 atm10 dev vx rdsk oracle816 oratest dev vx rdsk oracle816 oratest_bm atm20 dev vx rdsk oracle816 oratest dev vx rdsk oracle816 oratest_bm ip sync g oragroup 62 Site A primary host atm10 Site A host volume dev vx rdsk oracle816 oratest Site A host bitmap volume dev vx rdsk oracle816 oratest_bm Site B secondary host atm20 Site B host volume dev vx rdsk oracle816 oratest Site B host bitmap volume dev vx rdsk oracle816 oratest_bm Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Transmission protocol ip Replication mode sync 1 0 groupname An I O group name can be specified using the g character In this example it is oragroup To Shut Down the Site A Database At Site A shut down the production database if it is running by using the following Oracle command shutdown immediate or shutdown transactional Disable the remote mirror software and discard the remote mirror bitmap sndradm dn f etc opt SUNWrdc rdc cf Edit the rdc cf file to swap the Site A primary host information and Site B secondary host information For
45. effortlessly m Reduce maintenance costs a Minimize downtime and thus increase productivity m Take point in time snapshot copies of data from the secondary site using the Sun StorEdge Availability Suite Point in time Copy software m Provide easier failover fallback and reverse role scenarios 2 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Overview The remote mirror software is a remote replication facility for the Sun Solaris operating environment It is intended for use as part of a disaster recovery and business continuance plan to provide redundant storage of critical information across physically separate sites The remote mirror software enables you to replicate disk volumes between physically separate primary and secondary sites in real time As part of a disaster recovery and business continuance plan the remote mirror software enables you to keep up to date copies of critical data at remote sites You can also rehearse your data recovery strategy to failover data to remote sites Later you can write any data changes that occurred to the original disk that failed To transport data the remote mirror software uses any Sun network adapter that supports TCP IP The remote mirror software volume set consists of a primary volume residing on a local site and a secondary volume residing on a remote site The volume set also includes a bitmap volume on each si
46. er 0 can be part of a logical volume that is replicated m Volume size The size of the secondary site volume must be equal to or greater than the corresponding primary site volume If you initiate a remote mirror volume set where the secondary volume is larger than the primary a warning message appears but the transaction is allowed to continue If you initiate a volume set where the secondary volume is smaller than the primary volume the remote mirror command sndradm fails with an error Bitmap volume Each volume to be replicated requires a bitmap volume in the volume set The bitmap size can be calculated using the following formula 1 Kbytes 4 Kbytes per Gbyte of device storage space For example a 2 Gbyte data device requires a bitmap size of 9 Kbytes You can create bitmaps that are larger than the calculated size Also round up any partial Gbyte counts to the next Gbyte See also Bitmap Volume Configuration on page 34 30 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December To determine the volumes to be replicated using the remote mirror software you must balance remote accessibility and recoverability against capacity usage and I O response time Typically for the Oracle database you can include the following volumes in the remote replication configuration For data that is constantly changing Online logs Control files Data files typical
47. guring The Remote Mirror and Oracle Software This chapter describes installation requirements and configuration procedures for the remote mirror and Oracle software Topics described include a Installation Requirements on page 26 m Configuring the Remote Mirror Software on page 27 Installing and Configuring Oracle on page 36 25 Installation Requirements Operating Environment Oracle and Sun StorEdge Software Supporting Software Optional Recommended Software Host Types Hardware Supported Attached Storage Operating environment e Solaris 8 e Solaris 9u3 and later Oracle database software versions 8 and 8i Sun StorEdge Availability Suite 3 2 remote mirror software TCP IP network transport software such as SunATM or Gigabit Ethernet transports Sun StorEdge Availability Suite 3 2 point in time copy software install this package for additional point in time copy capability The remote mirror software is supported on server hosts using the Solaris operating environment and any network interface card supported by Sun Hosts include but are not limited to e Sun Enterprise 220R 250 420R and 450 servers e Sun Enterprise 3500 4500 5500 6500 and 10000 servers e Sun Fire 3800 4800 4810 and 6800 servers e Sun Fire 15K server e Sun Ultra 60 and 80 workstations e Sun Blade 100 and 1000 workstations e Sun Netra t 1400 1405 and 1120 1125 servers A CD ROM dr
48. he full database perform a reverse update synchronization also known as resilvering for archived logs online logs and control file volumes Make sure that your configuration file specified by config file contains the correct volumes Note Perform the following command at Site A sndradm un f config file After this step Site A returns to the normal replicating mode Chapter 3 Failover Scenarios 51 2 If you are replicating a file system run the sck 1M command for the replicated volumes before mounting them fsck dev vx rdsk diskgroup volume mount mount point 3 Start up and mount the database as a production database with the necessary secondary archive log destination specified in initsid ora startup pfile path initsid ora mount alter database recover automatic database alter database open 4 Perform the following steps at Site B a Start the database in nomount state startup pfiles path initsid ora nomount b Mount the standby database and recover the database alter database mount standby database recover managed standby database 52 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Switching Back to Site A as the Production Database By Restoring a Backup Copy Note This recovery scenario describes restoring a backup database copy from Site B to Sit
49. he rdc cf man page for more information about this configuration file format 32 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December TABLE 2 3 Volume Set File Format Fields Field Meaning Description phost Primary host Server on which the primary volume resides In this guide Site A pdev Primary device Primary volume partition Specify full path names only for example dev rdsk c0t1d0s4 pbitmap Primary bitmap Volume partition in which the bitmap of the primary partition is stored Specify full path names only shost Secondary host Server on which the secondary volume resides In this guide Site B sdev Secondary device Secondary volume partition Specify full path names only sbitmap Secondary Volume partition in which the bitmap of the secondary partition is bitmap stored Specify full path names only ip Network transfer Specify ip sync async g io groupname protocol Operating mode I O group name sync is the mode where the I O operation is confirmed as complete only when the remote volume has been updated async is the mode where the primary host I O operation is confirmed as complete before updating the remote volume An I O group name can be specified using the g character In this example it is oragroup Chapter 2 Configuring The Remote Mirror and Oracle Software 33 Bitmap Volume Configuration Note After editing the usr ke
50. iling Over to Site B on page 46 After the network or Site A failure problem is fixed these steps describe how to reverse the roles of the sites Site A will store the standby replicated database and Site B will store the production database In this scenario you must edit the configuration files for both hosts Volume Set File Used in This Example In this section the example remote mirror volume set file is named etc opt SUNWrdc rdc cf Following is the entry in the rdc cf file showing Site A atm10 and Site B atm20 details See also Creating a Remote Mirror Volume Set File on page 32 atm10 dev vx rdsk oracle816 oratest dev vx rdsk oracle816 oratest_bm atm20 dev vx rdsk oracle816 oratest dev vx rdsk oracle816 oratest_bm ip sync g oragroup Site A primary host atm10 Site A host volume dev vx rdsk oracle816 oratest Site A host bitmap volume dev vx rdsk oracle816 oratest_bm Site B secondary host atm20 Site B host volume dev vx rdsk oracle816 oratest Site B host bitmap volume dev vx rdsk oracle816 oratest_bm Transmission protocol ip Replication mode sync Chapter 3 Failover Scenarios 57 1 0 groupname An I O group name can be specified using the g character In this example it is oragroup To Shut Down the Site A Database At Site A shut down the production database if it is running by using the following Oracle command shutdown immediate or shutdown transaction
51. ive connected to the host server where the Sun StorEdge software is to be installed The remote mirror software is storage hardware independent Allocate approximately 15 Mbytes for the Sun StorEdge Availability Suite software installation e The remote mirror software requires approximately 1 7 Mbytes e The Sun StorEdge configuration location requires 5 5 Mbytes e Supporting packages require approximately 5 4 Mbytes Oracle disk space and memory requirements e Oracle binaries require approximately 1 Gbytes e Also required is a minimum 128 Mbytes of memory 512 Mbytes or greater recommended e Volume manager required 26 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Configuring the Remote Mirror Software The remote mirror configuration steps are as follows 1 2 N DD GF fe Determine the application replication requirements Set up the replicating TCP IP network link Allocate storage for the remote mirror volumes for the primary and secondary hosts Allocate the remote mirror bitmap volumes Install the remote mirror software Create an optional remote mirror configuration file Perform the initial volume replication using the remote mirror software Determining Application Replication Requirements Before you start planning the actual remote mirror configuration you must fully understand your application requirements for consi
52. ization from the primary system to its secondary system when the secondary volumes are stale from the interruption 1 The remote mirror software on host1 examines a bitmap from the primary and secondary hosts for the remote mirror software managed volumes affected by the interruption 2 The software on host1 requests the blocks that were updated during the interruption from the up to date volume The data might already reside in the host1 data cache or on the local disk 3 The software on host1 transmits the update blocks 3R to host 2 remote mirror software 4 The software on host2 refreshes its stale replicated image with the updated blocks and acknowledges the action to host1 5 The software revises the bitmap to track the remote update All steps repeat until the remote replicated image is updated Site A Primary Site B Secondary Disk Disk Cache HBA HBA Cache host host2 4 R 5 RM 1 1 2 A 4 a i bitmap U i3R p to date Stale remote 5 local disk TCP IP disk 3R FIGURE 1 4 Update Resynchronization of a Secondary Volume Set Chapter 1 Introduction to the Remote Mirror Software 17 Reverse Full Synchronization During reverse full synchronization the remote mirror software replicates the volume data from the secondary site to the primary site After you issue the sndradm m r command the softw
53. ly multi volume Index files typically multi volume Rollback segments typically multi volume Archived logs For data that seldom changes or can be reconstructed Static tablespace data files Temporary tablespace data files Do not include the following as remote mirror volumes Spool files Paging volumes Oracle binary Other UNIX binary volumes v To Create and Set Up Volumes 1 Create disk groups using volume manager software such as Sun Solstice DiskSuite Create the following volumes a A volume for the Oracle binary not to be replicated m One or more volumes for the database data files a A volume for online logs m A volume for the archive log files if utilizing full database replication Install the remote mirror software See the Sun StorEdge Availability Suite 3 2 Software Installation Guide for details Create directories under the root directory as mount points for volumes Chapter 2 Configuring The Remote Mirror and Oracle Software 31 5 If a file system is used then create the entries in the etc vfstab file At Site B do not mount the remote mirror volumes automatically See About Replicating File Systems About Replicating File Systems The remote mirror software is not a file or file system replicator It is a volume replicator When you replicate a volume on the primary Site A to a volume on the secondary Site B Site B receives an exact bit for bit copy Make sure that a
54. meaning that it can use any Sun network adapter that supports TCP IP Continue remote data access despite local disk failure depending on how the remote mirror software is configured Disk Based Asynchronous Queues In the 3 2 version of the remote mirror software data can be queued on disk as well as in memory Memory based queues are the default Disk based queues enable m Larger local queues in asynchronous replication mode m Larger bursts of I O activity without affecting application response time If a disk based queue fills up the remote mirror software goes to nonblocking or scoreboarding mode Chapter 1 Introduction to the Remote Mirror Software 5 6 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December One to Many Many to One and Multihop Volume Sets The remote mirror software enables you to create one to many many to one and multihop volume sets One to many replication enables you to replicate data from one primary volume to many secondary volumes residing on one or more hosts One primary and each secondary site volume is a single volume set For example with one primary and three secondary host volumes you need to configure three volume sets primary A and secondary B1 primary A and secondary B2 and primary A and secondary B3 Many to one replication enables you to replicate volumes across more than two hosts through more than one network conn
55. nting them fsck dev vx rdsk diskgroup volume mount mount point 3 Full database replication only Recover the database and open it as a production database using the following Oracle commands Otherwise skip to Step 4 Chapter 3 Failover Scenarios 47 a Start the database in mount mode startup pfiles path initsid ora mount b Recover the database alter database recover automatic database c Open the database as the production database alter database open noresetlogs 4 For Standby Databases Only Open the Site B standby database as a production database using the following Oracle commands a Start the database in nomount state startup pfile path initsid ora nomount b Mount the standby database alter database mount standby database c Recover the database alter database recover automatic standby database d Open the database as the production database alter database activate standby database 5 Shut down the database and make a cold backup copy shutdown immediate perform the cold back up 48 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December 6 Open the database startup pfiles path initsid ora mount alter database read write Switching Back to Site A as the Production Database By Copying Files Note
56. ny Site A file systems you want to replicate are mounted When replicating the primary host file system is mounted Do not mount the file system on Site B until you are ready to fail over or write to that site s volume Changes appear on a replicated file system volume only after mounting the volume Creating a Remote Mirror Volume Set File When you enable the remote mirror software you can specify an optional volume set file containing information about the volume set volumes Site A and Site B hosts bitmaps operating mode and so on Use the sndradm f volset file option when you use a volume set file You can also enter information about each volume set from the command line but it might be more convenient to put this information in a file when you have multiple volume sets One advantage when using one or more volume set files is that you can operate on specific volume sets and exclude other sets from the operation Unlike adding the volume sets to an I O group you can mix replication modes in a volume set file The fields for the configuration file specified using the config file option are phost pdev pbitmap shost sdev sbitmap ip sync async g io groupname An example configuration file entry is as follows atm10 dev vx rdsk oracle816 oratest dev vx rdsk oracle816 oratest_bm atm20 dev vx rdsk oracle816 oratest dev vx rdsk oracle816 oratest_bm ip sync g oragroup See TABLE 2 3 See t
57. opied to the target volume After the update is complete the software maintains the normal replicating mode The software can also be placed in logging mode See Logging on page 20 The software resynchronizes the secondary volume from the primary volume It updates the secondary volume according to the changes based on logs maintained while replication was stopped It also enables concurrent replication between the primary and secondary volumes any new write operations to the primary volumes are also replicated to the secondary volumes If a remote copy interruption lasts numerous hours and the updates are widespread logging and update resynchronization provide diminishing returns As time passes the proportion of bits set to true in the bitmap volumes of a volume set might reach 100 percent The overhead of logging coupled with update resynchronization must then be balanced against that of a full synchronization without intervening periods of logging Logging and update resynchronization serve as a built in safety net should one of your replication processes be interrupted The software monitors the network connections between the primary and secondary hosts Link failures and remote system failures are detected by the transport interface and are passed to the remote mirror software Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December FIGURE 1 4 shows an update resynchron
58. quired for the remote mirror software to switch from replicating mode to logging mode m Asynchronous mode replication The database or application gets the write operation acknowledgment immediately as soon as the bitmap is set The following steps show how to resynchronize the sites after a link failure To Manually Place the Remote Mirror Software into Logging Mode Perform this step from Site A if you want simulate a link failure which will place both sites into logging mode To start logging usr opt SUNWesm sbin sndradm ln f config file See Creating a Remote Mirror Volume Set File on page 32 Chapter 3 Failover Scenarios 45 v To Resynchronize Site B from Site A Note Perform these steps from Site A 1 Make sure that Site A and Site B show they are in logging mode using the dsstat command After the network link is restored 2 Perform fast synchronization to update the volumes at Site B sndradm un f config file After this step Site A replicates the changes to Site B You can monitor this process using the scmadm SM command Once the replication is finished Site A and Site B resume the normal replicating mode Failing Over to Site B Note This recovery scenario describes switching the production database to Site B If Site A is not accessible business users must connect to an alternate site Site B to continue operations Use the following proce
59. r X Open Company Ltd Sun Sun Microsystems le logo Sun AnswerBook2 docs sun com Sun StorEdge Solstice Disk Suite Sun ATM Sun Enterprise Sun Fire et Solaris sont des marques de fabrique ou des marques d pos es de Sun Microsystems Inc aux Etats Unis et dans d autres pays Toutes les marques SPARC sont utilis es sous licence et sont des marques de fabrique ou des marques d pos es de SPARC International Inc aux Etats Unis et dans d autres pays Les produits protant les marques SPARC sont bas s sur une architecture d velopp e par Sun Microsystems Inc L interface d utilisation graphique OPEN LOOK et Sun a t d velopp e par Sun Microsystems Inc pour ses utilisateurs et licenci s Sun reconna t les efforts de pionniers de Xerox pour la recherche et le d veloppment du concept des interfaces d utilisation visuelle ou graphique pour l industrie de l informatique Sun d tient une license non exclusive do Xerox sur l interface d utilisation graphique Xerox cette licence couvrant galement les licenci es de Sun qui mettent en place l interface d utilisation graphique OPEN LOOK et qui en outre se conforment aux licences crites de Sun LA DOCUMENTATION EST FOURNIE EN L TAT ET TOUTES AUTRES CONDITIONS DECLARATIONS ET GARANTIES EXPRESSES OU TACITES SONT FORMELLEMENT EXCLUES DANS LA MESURE AUTORISEE PAR LA LOI APPLICABLE Y COMPRIS NOTAMMENT TOUTE GARANTIE IMPLICITE RELATIVE A LA QUALITE MARCHANDE A L APTITUDE A
60. rage Systems for Oracle Database by J Bill Lee Cynthia Yip Oracle 4 Sun StorEdge Network Data Replicator Oracle Database Implementation Guidelines by Judy Leach Philip Crane Sun Microsystems Inc 69 5 Oracle Installation Manual for 8 1 7 Solaris 6 Sun StorEdge Availability Suite 3 2 Software Installation Guide 7 Sun StorEdge Availability Suite 3 2 Remote Mirror Software Administration and Operations Guide 70 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Glossary Asynchronous replication Configuration location Forward resynchronization Full synchronization Logging Primary or local host or volume Asynchronous replication confirms to the originating host that the primary I O transaction is complete before updating the remote image That is completion of the I O transaction is acknowledged to the host when the local write operation is finished and the remote write operation has been queued Deferring the secondary copy removes the long distance propagation delays from the I O response time Location where the Sun StorEdge Availability Suite software stores configuration information about all enabled volumes used by the software See Update synchronization Full synchronization performs a complete volume to volume copy which is the most time consuming of the synchronization operations In most cases a secondary volume is synchronized
61. re on host 1 requests the blocks updated during the interruption from the up to date secondary volume of host 2 The data might already be resident in host2 s data cache or it might require secondary disk access 3 The software on host2 transmits the updated blocks 3R to host 1 remote mirror software region of cache using the intersite link 4 The software on host1 refreshes its stale image with the updated blocks 5 The software on host1 revises the bitmap to track the remote update All steps repeat until the primary volume is up to date Chapter 1 Introduction to the Remote Mirror Software 19 20 Site A Primary Site B Secondary Disk Disk Cache HBA HBA Cache host1 host2 RM gt 7 hp dis SR 5 4 l4 i 2 RE bitmap a bitmap 7 Stale Up to date V3 Mai A local disk TCP IP secondary disk eet Fe oo 1R 3R Copy of secondary bitmap FIGURE 1 6 Reverse Update Synchronization Logging Note With synchronous and asynchronous replication the remote mirror software automatically switches to logging mode if a break in the network occurs or if the primary site is down During logging the remote mirror software only updates the bitmaps at the primary site no replication occurs At a later time the bitmaps at the primary and secondary sites are compared and the changed blocks in the primary si
62. rnel drv rdc conf file reboot your server The remote mirror version 3 2 software does not support bitmap files The remote mirror software uses regular raw devices to store bitmaps used to maintain the remote mirror bitmap For example you can specify a bitmap volume as dev rdsk c6t0d0s4 These raw devices should be stored on a disk separate from the disk that contains the data Configure RAID such as mirrored partitions for these bitmap devices and ensure that the mirrored members are not stored on the same disk as the data A bitmap maintained on disk can persist across a system crash depending on the setting of rdc bitmap mode in usr kernel drv rdc conf For example rdc bitmap mode Sets the mode of the RDC bitmap operation acceptable values are autodetect bitmap mode depending on the state of SDBC default force bitmap writes for every write operation so an update resync can be performed after a crash or reboot only write the bitmap on shutdown so a full resync is required after a crash but an update resync is required after a reboot HHH HH HH rdc bitmap mode 1 0 1 34 If your server is not configured in a clustered environment you can also choose the bitmap mode setting of 1 to improve error or disaster recovery Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Enabling and Replicating the Remote Mirror Volumes For
63. stency and the application recovery methods First you must decide which data requires replicating and the mode of replication to be used A number of methods are available Replicate volumes using a mix of synchronous and asynchronous modes according to the volumes level of importance This mode choice provides the most practical solution and is the method detailed in this document Replicate all volumes in synchronous mode This mode choice simplifies procedures because data at the primary and secondary sites is identical apart from any data lost in transit during a failure It is reliable and can help reduce the risk of data loss one disadvantage might be an increase in response time especially for large data sets or long distance replication Chapter 2 Configuring The Remote Mirror and Oracle Software 27 28 m Replicate all volumes in asynchronous mode This mode choice might allow the possibility of lost transactions during system failures and might result in the database being inconsistent The advantages of asynchronous replication are that it provides fast response and has the least impact on the response time of the primary application The disadvantage is that there is a possibility of data loss at the secondary site after primary site or network failures The database files can be grouped based on the requirements for their availability and the importance for the application recoverability process as shown in TABLE 2 1
64. tartup pfile path initsid ora no mount Create the control file using the script created in Step 1 create controlfile Mount the database alter database mount Recover the database and open it alter database recover automatic database alter database open Chapter 3 Failover Scenarios 55 7 Create the standby control file and set the archive destination alter database create standby control file alter system archive log current alter system set log archive dest state 2 enable alter system set log archive min succeed dest 2 8 Copy the control file to Site B 9 At Site B start the database in nomount state startup pfile path initsid ora no mount 10 At Site B mount the database as the standby database alter database mount standby database 11 At Site B recover the standby database recover managed standby database 12 At Site A open the database 56 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Swapping Host Roles Database Copy Note This recovery scenario fails Site A over to Site B Site B then becomes the primary remote mirror host and Site A becomes the secondary remote mirror host After the failover is activated Site B is used for the production database To fail over to Site B execute the failover steps described in Fa
65. te to track write operations and differences between the volumes The remote mirror software is active while your applications are accessing the data volumes and continually replicates the data to remote sites The software operates at the volume level on storage devices attached to one or more hosts You can update the data on the secondary volume by issuing a command to resynchronize the volumes You can also restore data from the secondary volume to the primary volume by issuing a command to reverse resynchronize the volumes Chapter 1 Introduction to the Remote Mirror Software 3 4 Features TABLE 1 1 describes the remote mirror software features TABLE 1 1 Remote Mirror Software Features This Feature Enables You To Active logging Disaster rehearsal rollback Groups of remote mirror volume sets Disk based asynchronous queues Multihop sets Mutual backup One to many sets Optimized resynchronization RAID support Continue logging operations whenever the remote mirror software is disabled or interrupted Simulate a disaster without committing data changes to volumes Control the remote mirror software volume sets simultaneously by grouping them This feature is essential in installations requiring you to maintain consistent contents of a group of volumes A group is a collection of remote mirror software sets that have the same group name primary and secondary interfaces and mirroring
66. te volume are mirrored by update resynchronization to the secondary site If all volume sets in an I O group are replicating that is the secondary volumes contain a valid point in time copy of the corresponding primary volumes when one volume set enters logging mode all other sets in the I O group will enter logging mode automatically This scheme ensures that the secondary volumes will contain a valid copy of the data You can use logging to save on telecommunications or connection costs The risk however is the costs incurred by increased data loss if the primary site is lost If you lose the primary site you do not have the data at the secondary site that was written to the primary site during logging Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December You can also perform logging on the secondary site before a failover You can then update the primary site using a reverse synchronization or reverse update synchronization command Note To resume remote mirror software operations after using the sndradm 1 logging command use the sndradm m command to perform a full resynchronization or the sndradm u command to perform an update resynchronization Note also that when issued from the secondary host the sndradm 1 command does not work on the secondary volume for any volume that is currently synchronizing Chapter 1 Introduction to the Remote Mirror Software 21
67. ters logging mode and Site A continues to operate normally While the remote mirror software is designed to reduce the negative impact of data unavailability at one site by keeping secondary copies it cannot prevent data unavailability For example a Site A host failure while the remote mirror software is suspended and logging can result in Site B data that is current only to the time when logging began on Site A The remote mirror software does not prevent data corruption from software bugs operator errors or hardware failures In fact the remote mirror software might faithfully replicate some of these anomalies to Site B volumes as part of the data replication process Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December Link Failures Note For information about the usr opt SUNWesm sbin sndradm command see the Sun StorEdge Availability Suite 3 2 Remote Mirror Software Administration and Operations Guide If the network link fails and replication is occurring in synchronous mode or asynchronous mode the remote mirror software at Site A enters logging mode after a time out The bitmap bits are set according to any changes in the data area The remote mirror software then acknowledges to the database or application that the write operation is complete Synchronous mode replication The database might freeze momentarily during the time out that is the time re
68. the Site A Database 63 v To Shut Down Site B and Enable the Remote Mirror Software 64 v To Perform a Full Database Replication and Start the Database 65 v To Start the Database at Site A 66 Contents v Implementing One To Many Replication 67 Implementing Multihop Replication 68 4 Conclusions 69 References 69 vi Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December CHAPTER 1 Introduction to the Remote Mirror Software Note This software was previously known as the Sun StorEdge Network Data Replicator Sun SNDR software This chapter describes the following Why Should You Use Data Replication on page 2 Overview on page 3 Architecture on page 10 Replication Modes on page 12 Synchronization Modes on page 14 Using the Remote Mirror Replication with Oracle on page 22 Why Should You Use Data Replication In today s world of Internet accelerated business practices companies must meet the demand for 24x7 online communications and operations to remain successful The business costs of application outages are increasing Outages can result from major power server and communications disruptions and natural disasters The potential consequences of application outages are revenue losses missed opportunities poor customer relations fines and even business failure Businesses are searching for ways to redu
69. the remote mirror software sndradm en f etc opt SUNWrdc rdc cf m If you are performing a full database replication see To Perform a Full Database Replication and Start the Database on page 60 a If you replicating the online logs only see To Replicate the Online Log Files Only on page 60 Chapter 3 Failover Scenarios 59 v To Perform a Full Database Replication and Start the Database Note Perform these steps at Site B 1 Perform a full synchronization from Site B to Site A sndradm mn f etc opt SUNWrdc rdc cf 2 Start the database in open mode using the following Oracle command startup pfile path initsid ora 3 Proceed to To Start the Database at Site A on page 61 v To Replicate the Online Log Files Only Note Perform these steps at Site B 1 Create a standby control file make the archive log current and enable the secondary destination of the archived logs alter database create standby control file filename alter system archive log current alter system set log archive dest state 2 enable alter system set log archive min succeed dest 2 2 Copy the data files and standby control files to Site A using the cp 1M copy command 3 Proceed to To Start the Database at Site A on page 61 60 Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December vy 1
70. the source or primary volume in logging mode Make sure that the backup copy is a physical copy for example by using the dd 1M command and not a logical copy for example one made using the tar 1M or cpio 1M commands The copies must have identical blocks not just identical files FIGURE 1 3 shows the full forward synchronization process 1 The remote mirror software on the primary system host1 requests disk blocks from the active primary volume The data might already be resident in the primary system data cache or might require a local disk access 2 The software transmits the disk blocks with destaging instructions over the connection to a cache region on the secondary system 3 The software on the secondary system updates its remote volume and acknowledges the update to the primary system Chapter 1 Introduction to the Remote Mirror Software 15 Site A Primary Site B Secondary Disk Disk Cache HBA HBA Cache host1 host2 r RM v E3 Local Remote E disk TCP IP disk eo dome nn es J 16 FIGURE 1 3 Full Synchronization Volume to Volume Copy Update Resynchronization During update resynchronization mirroring the remote mirror software initiates replication of only the changed primary site volume data to the secondary site based on the bitmap Only the blocks marked dirty in the bitmap are c
71. volumes to Site A Depending on your volume needs and your site requirements you can also replicate Site C to Site B to Site A When replicating between Site A and Site B place the Site B to Site C volumes in logging mode Usage Guide for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases December CHAPTER 4 Conclusions 1 For both log file replication and full database replication the remote mirror software might not lose any committed data while running in synchronous mode Log file replication as used here had the least impact on performance 2 Running the remote mirror software in asynchronous mode might further improve performance since the application is not required to wait for the acknowledgement from the secondary site 3 Replicating the entire database might impact system performance especially as the distance between sites increases Note Both replication modes offer different fall back and failover procedures The choice of one mode or the other depends on the nature of the business the transaction volume and the allowable down time during disaster recovery References 1 Sun Test Results for Sun StorEdge Availability Suite 3 2 Remote Mirror Software with Oracle Databases by Sridhar Ranganathan Sun Microsystems 2 Guidelines for Using Remote Mirroring Storage Systems for Oracle Database by J Bill Lee Oracle 3 Guidelines for Testing Remote Mirroring Sto

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