EXB-8500 MID-TAPE WAKE
Contents
1. 8mm Cartridge Tape Subsystem EXB 8500 You can use this document as a supplement to the EXB 8500 Cartridge Tape Subsystem User s Manual part number 510201 About This Command July 1992 The MID TAPE WAKE UP command is an EXABYTE unique command that is implemented using the vendor unique feature of the SCSI LOAD UNLOAD command Important MID TAPE WAKE UP is an optional command requiring a special EEPROM image from EXABYTE This EEPROM image is not included in standard EXB 8500s If your EXB 8500 includes the special mid tape wake up EEPROM other EEPROM options are not available instead the EXB 8500 is shipped in a standard configuration The MID TAPE WAKE UP command provides a second power on mode that enables the EXB 8500 to recover from a powered off state faster than it can in its normal power on mode Specifically the MID TAPE WAKE UP command allows an EXB 8500 to power on without reloading the tape or repositioning the tape to LBOT To shorten the power on sequence further in mid tape wake up mode an EEPROM option allows you to request a full or an abbreviated RAM test of the 1 MByte data buffer when the EXB 8500 is powered on in mid tape wake up mode Since the integrity of any data transferred through the buffer cannot be guaranteed if the RAM is not tested this option is designed for applications where you want to continue capturing data even if a portion of the buffer fails Command Descriptor Block Mid2. and you have not put the EXB 8500 to sleep You have just powered on the EXB 8500 and you issue a MID TAPE WAKE UP command with the MTW Function field set to 000b Sleep After you power on the EXB 8500 in mid tape wake up mode you must first issue a MID TAPE WAKE UP command with the MTW Function field set to 001b Wake Up This allows the EXB 8500 to properly position the tape for subsequent operations July 1992 9 Exceptions and Error Conditions Hardware Errors If an unrecoverable hardware error occurs during a mid tape wake up operation the EXB 8500 terminates the MID TAPE WAKE UP command and returns Check Condition status The sense key indicates a Hardware Error 4h As shown in Table 3 indicators in the extended sense data can be used to isolate the error Table 3 Extended sense data for mid tape wake up Hardware Error conditions Description of error Warning The EEPROM is nearing the end of its expected lifetime This error occurs when you have saved the tape s logical position approximately one million times The reliability of the EEPROM cannot be guaranteed past one million save operations Error An attempt to program the EEPROM has failed 10 A servo hardware error was encountered 510208
3. high speed search operations cannot be reliably performed near the end of the data July 1992 3 Field Definitions Setting of MTW Function field Name of function Description of mid tape wake up function Finish Disable mid tape wake up mode Issuing a MID TAPE WAKE UP command with the MTW Function field set to 101b returns the EXB 8500 to its normal operating mode Reserved Byte 05 Bit 7 MTW These bit settings are reserved If you set the MTW Function field to one of these values This bit distinguishes between the LOAD UNLOAD command and the EXABYTE unique MID TAPE WAKE UP command as follows 0 This is a LOAD UNLOAD command refer to the EXB 8500 User s Manual 1 This is the EXABYTE unique MID TAPE WAKE UP command Byte 05 Bit 6 Vendor Unique There are no vendor unique definitions for this bit 510208 Using Mid Tape Wake Up Mode Using Mid Tape Wake Up Mode July 1992 Important Because mid tape wake up mode allows tapes to be created without an EOD mark you should use a new or erased tape Otherwise high speed search operations cannot be reliably performed near the end of the data on a tape written in mid tape wake up mode Starting Mid Tape Wake Up Mode To use mid tape wake up mode follow these steps 1 Initialize a tape for mid tape wake up data logging by loading a blank data cartridge and writing two long filemarks This
4. EPROM is replaced by qualified service personnel after each one million sleep wake up cycles Note The power on default for removing a cartridge from an EXB 8500 with a mid tape wake up EEPROM is to inhibit removal If you want to remove the cartridge from the EXB 8500 issue a PREVENT ALLOW MEDIUM REMOVAL command with the Prevent bit set to 0 8 510208 Exceptions and Error Conditions Exceptions and Error Conditions The following exceptions and error conditions can occur with the EXABYTE unique MID TAPE WAKE UP command Illegal Request If you issue an invalid MID TAPE WAKE UP command the EXB 8500 terminates the command and returns Check Condition status The sense key indicates Illegal Request 5h As shown in Table 2 indicators in the extended sense data can be used to isolate the error Table 2 Extended sense data for mid tape wake up Illegal Request conditions Description of error You have issued a MID TAPE WAKE UP command with the MTW Function field set to a reserved value for valid values see Table 1 You have issued a MID TAPE WAKE UP command with the MTW Function field set to anything other than 010b Set Up and the EXB 8500 is not in mid tape wake up mode You have issued a MID TAPE WAKE UP command with the MTW Function field set to 010b Set Up and the EXB 8500 is already in mid tape wake up mode You have issued a MID TAPE WAKE UP command with the MTW Function field set to 001b Wake Up
5. EXB 8500 8mm Cartridge Handling Subsystem MID TAPE WAKE UP Command 1Bh sExabyte 510208 000 Copyright Copyright 1992 by EXABYTE Corporation All rights reserved This item and the information contained herein are the property of EXABYTE Corporation No part of this document may be reproduced transmitted transcribed stored in a retrieval system or translated into any language or computer language in any form or by any means electronic mechanical magnetic optical chemical manual or otherwise without the express written permission of EXABYTE Corporation 1685 38th Street Boulder Colorado 80301 Trademark Notices EXABYTE is a registered trademark and EXATAPE is a trademark of EXABYTE Corporation All other brand and product names are trademarks or registered trademarks of their respective companies EXABYTE Corporation 1685 38th Street Boulder Colorado 80301 303 442 4333 510208 000 Contents IIPOGUCHON o s oa ce a os ete eee we Oe eke 1 About This Command 62 0 4 2064 2422 ee wees 1 Command Descriptor Block 2 Field Definitions ie hie dk ew Re ee ee Re wd 2 Using Mid Tape Wake Up Mode 5 Time Required for Mid Tape Wake Up Mode 7 Adding Mid Tape Wake Up Capability to an EXB 8500 8 Exceptions and Error Conditions 9 Introduction Introduction This document describes the MID TAPE WAKE UP 1Bh command for the EXABYTE EXB 8500
6. Using mid tape wake up mode lessens the time it takes the EXB 8500 to become ready to write data to tape after power on In normal power on mode the EXB 8500 performs a full RAM test of the 1 MByte buffer and rewinds the tape to LBOT These activities take a minimum of 55 seconds to complete In mid tape wake up mode the EXB 8500 performs either a full or an abbreviated RAM test whichever you specify in the EEPROM option and rather than rewinding the tape to LBOT logically positions the tape between the two filemarks written before the EXB 8500 was powered off With a full RAM test the EXB 8500 takes 45 seconds to become ready With an abbreviated RAM test the EXB 8500 takes 25 seconds to become ready July 1992 Adding Mid Tape Wake Up Capability to an EXB 8500 Adding Mid Tape Wake Up Capability to an EXB 8500 If you want to add mid tape wake up capability to an EXB 8500 you can receive a special microcode load tape from EXABYTE This load tape causes the EEPROM to be initialized for mid tape wake up use The initialized EEPROM has the count of mid tape wake up sleep wake up cycles set to 0 Note For instructions on using a microcode load tape see the EXB 8500 User s Manual A mid tape wake up EXB 8500 will issue a warning after approximately one million sleep wake up cycles After this warning the EEPROM will continue to function until it becomes unreliable To avoid using an unreliable EEPROM be sure that the E
7. cates what function occurs based on the setting of this field Table 1 Mid tape wake up functions Setting of MTW Function field Name of funchon Description of mid tape wake up function Prepare for power off Save the tape s current 000b Sleep logical position in the EEPROM and release the tension on the tape Move the tape to the logical position saved by the Wake Up last Sleep or Set Up function executed before power off Enable mid tape wake up mode and record the tape s current logical position in the EEPROM Note Even though the EEPROM is set for mid tape wake up the EXB 8500 will act just like a normal EXB 8500 until you enable mid tape wake up mode by issuing a MID TAPE WAKE UP command with the MTW function field set to Set Up Unload the data cartridge without rewinding the tape Note When you issue a MID TAPE WAKE UP command with the MTW Function field set to 01 1b the EXB 8500 does not empty the data buffer write an EOD mark or rewind the tape before it unloads the data cartridge For this reason only use this function if absolutely necessary This function is provided for applications that cannot afford the power and time needed to write an EOD mark and rewind the tape after data logging is complete It allows the tape to be unloaded from the tape path and wound back into the cartridge immediately Unload Now A tape created with this function does not contain an EOD mark therefore
8. ensures that the tape contains a valid LBOT area and is logically positioned at a mid tape wake up splice point A mid tape wake up splice point consists of two long filemarks with no intervening data Issue a MID TAPE WAKE UP command with the MTW Function field set to 010b Set Up This activates mid tape wake up mode and causes the EXB 8500 to save the tape s current logical position in the EEPROM Write data to tape as you normally would When you are ready to power off the EXB 8500 write two long filemarks to the tape This provides a splice point that will be used when you resume write operations Issue a MID TAPE WAKE UP command with the MTW Function field set to 000b Sleep This saves the tape s current logical position in the EEPROM and causes the drum to release tape tension Using Mid Tape Wake Up Mode As soon as the EXB 8500 returns Good status power the EXB 8500 off The EXB 8500 does not rewind the tape write an EOD mark or flush the buffer Waking Up the EXB 8500 and Resuming Data Logging When you are ready to resume data logging activities follow these steps 1 Power the EXB 8500 back on The EXB 8500 a Performs a controller bootcode ROM self test b Performs a servo system self test The tape load unload activities are suppressed C Restores SCSI variables to their power on defaults d Tests the 1 MByte buffer In mid tape wake up mode an abbreviated RAM test is the default al
9. tape wake up mode is designed for special applications that require battery operation such as remote site data logging Typically these type of applications collect data and then periodically write that data to tape To reduce the drain on the batteries you can turn off the EXB 8500 until you are ready to transfer data Then when you power on the EXB 8500 you can quickly locate the tape to the last saved logical position before power off Command Descriptor Block The command descriptor block for the MID TAPE WAKE UP 1Bh command is shown below 0 0 0 1 0 Logical Unit Number Reserved Reserved Reserved Reserved Field Definitions Byte 01 Bit 0 Immed The Immed bit is used to determine when command status is returned to the initiator as follows 0 Status is reported to the initiator when the mid tape wake up operation is complete 1 Status is reported to the initiator when the command is initiated by the EXB 8500 Note To ensure that meaningful results are obtained do not set the Immed bit for mid tape wake up mode Unless command status is returned when the command is completed you would not be able to determine when it is safe to power off the CTS 510208 Field Definitions Byte 04 Bits 2 through 0 MTW Function The MTW mid tape wake up Function field indicates which mid tape wake up function you want to perform with this CDB Table 1 indi
10. though an EEPROM option lets you choose between a full RAM test or an abbreviated RAM test Issue a TEST UNIT READY 00h command to ensure that the EXB 8500 is ready The EXB 8500 will respond with Check Condition status Issue a REQUEST SENSE 03h command to report and clear the Unit Attention 6h sense key Issue a MID TAPE WAKE UP command with the MTW Function field set to 001b Wake Up The EXB 8500 a Re tensions the tape path and moves the tape back 50 tracks b Spaces backward at 1 5 times the normal tape speed if necessary to position the tape in front of the last saved logical position in the EEPROM This motion is necessary to recover from an unexpected power failure during data logging 510208 Time Required for Mid Tape Wake Up Mode C Reads forward at normal read speed The EXB 8500 logically positions the tape between the two filemarks written when you prepared the EXB 8500 for power off see step 4 in the previous section During this read operation EXB 8500 recalibrates its adaptive servo parameters 5 Issue a WRITE or WRITE FILEMARKS command to resume data logging The EXB 8500 will overwrite the second of the two long filemarks Returning to Normal Power On Mode If the EXB 8500 is in mid tape wake up mode and you want to begin using normal power on self test mode issue a MID TAPE WAKE UP command with the MTW Function field set to 101b Finish Time Required for Mid Tape Wake Up Mode
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