HP LTO 4 SAS, LTO 4 FC, LTO 4 SCSI manual see ”read-while-write”

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offline	The drive is offline if the tape is currently unloaded or not in the drive. The host has
	limited access, and cannot perform any commands that would cause tape motion. The
	host can, however, load a tape, if one is inserted, and can execute any diagnostic tests
	that do not require tape motion.
online	The drive is online when a tape is loaded. The host has access to all command
	operations, including those that access the tape, set configurations and run diagnostic
	tests.
RWW	see ”read-while-write”
read-while-write	RWW improves data integrity by reading data immediately after it is written and
	writing the data again if an error is found.
TapeAlert	A set of 64 flags is held in the TapeAlert log that indicate faults or predicted faults with
	the drive or the media. By reading this log, host software can inform the user of
	existing or impending conditions, and can, for example, advise the user to change the
	tape.
WORM	Write Once, Read Many

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Contents volume 2 software integration LTO 4 FC, SCSI and SAS drivesHP LTO Ultrium tape drives technical reference manual HP restrictedLegal and notice information Contents 1 Designing backup applications2 Configuration and initialization 3 Use of tapes5 Supporting Ultrium features 4 Factors affecting performance6 Sense keys and codes 7 Exception handlingHP restricted Related documents Documentation mapDocuments specific to HP Ultrium drives Drives-generalInstallation and configuration OperationCartridges InterfaceMaintenance and troubleshooting Dealing with errorsLTO Ultrium features General documents and standardization1 Designing backup applications Non-immediate commandsOptimizing performance Large data transfer sizeCleaning tape heads Managing the use of tapesInformation in Cartridge Memory Monitoring tape useDesign goals for LTO backup applications Diagnostic logsTapeAlert Displaying drive informationInclude the capability to download firmware Operating system drivers 2 Configuration and initializationInquiry string recovery SCSI protocol, regardless of transport or interface type Example16 Configuration and initialization Supporting additional LUNs Support for additional LUNEnabling additional LUN support 18 Configuration and initialization Using Cartridge Memory attributes Using MODE SENSE3 Use of tapes LTO cartridge memoryInterpreting Log Sense data Tape status and capacityFinding the remaining capacity CDB fields Using the SET CAPACITY commandCommand descriptor block Changes to SCSI commands WORM mediaHow WORM media works New additional sense codes and TapeAlert flagsError Usage page ERASE commands rejectedSET CAPACITY command Re-writing media labelsUnique media identifier Using CM to check tape integrityBehavior with a missing or inconsistent EOD value Barcode support Responding to Cartridge Memory dataLoad count RWW retry counts Corrective action4 Factors affecting performance Ways of optimizing performanceDetecting the drive’s speed Ensuring the recommended minimum transfer sizesUsing Cartridge Memory instead of tape headers Using the Performance Log page for diagnosing problemsTime-out values Media type identificationHost-related factors Recommended support of log pagesFactors affecting performance Example Recommendationwhere possible or a reasonably sized RAID system. More disks means makes sense to split heavily used FC cards across separate PCI bussesDrive-related factors Do not interleave write commands with other commands, such as READFormat-related factors Page 34 Factors affecting performance 5 Supporting Ultrium features Cartridge Memory LTO-CMAutomation interface Further informationAutomation/Device Interface ADI Slave to a library controller Automation Control Interface ACIModes of usage through ACI SCSI pass-through mode ACI command setACI commands that affect drive streaming performance New features in ACI Backward compatibilitySCSI command Encryption support Further details Supporting the ACI protocolRecommended ACI time-out values 42 Supporting Ultrium featuresRecommended power-up sequence Treatment of reserved fieldsRecommended load-unload configuration Firmware upgrade via tape Recommended Get Drive Status polling frequencyACI protocol communications retry Upgrading the drive firmwareFirmware upgrade via the primary host interface Firmware upgrade via ACILibrary firmware upgrade via tape Handling irregular cartridgesCleaning cartridge HP-configured or Universal Expired cleaning cartridge HP-configured or UniversalNon-HP Ultrium 1 cleaning cartridge Unreadable data cartridgeValid firmware upgrade cartridge Data cartridge with unreadable CMCartridge fails to seat or load Cartridge cannot be loadedFrequently asked questions CleaningInvalid firmware upgrade cartridge Is there separate firmware for drives intended to go into libraries?Backup software Resetting drivesResetting via the ACI Reset command Resetting using the ACIRSTL lineAccessing Cartridge Memory without threading the tape Controlling data compressionOther mode page information Buffer size at EW-EOMRewind on reset Write delay timePartition size 52 Supporting Ultrium features6 Sense keys and codes Sense keys-actions to takeAction Console Message“3h-MEDIUM ERROR” on page 62 . Also see the Media Access For additional sense codes, see “3h-MEDIUM ERROR” onlog the error, terminate I/O to the drive, and pass the appropriate error to the calling applicationAction Console MessageAction Console Messagepage Additional sense codes-actions to take PhysicalEnd-of-Tape reached, unable to fit0h-NO SENSE 1h-RECOVERED ERROR 2h-NOT READYThe software must issue a LOAD before media access LUN not accessible, port inThe command cannot be executed because the specified 60 Sense keys and codesmechanism tests are being executed. When the tests are 62 Sense keys and codes 3h-MEDIUM ERRORA READ , SPACE , WRITE or WRITE FILEMARKS command Send a console message that an unrecovered error on and the drive. Based on this, ask the user to clean the64 Sense keys and codes Send a message to the console indicating that there is The current command such as READ, SPACE, REWIND 66 Sense keys and codes4h-HW ERROR 68 Sense keys and codes 5h-ILLEGAL REQUESTA MODE SELECT parameter list sent to the drive contains 6h-UNIT ATTENTION persistent reservation using the PERSISTENT RESERVE OUTallowed to execute. In other words, some commands can 32 initiators to register, using PERSISTENT RESERVE OUTAction service action removed all reservations and the persistent A PERSISTENT RESERVE OUT command was executedWRITE BUFFER or MAINTENANCE OUT command A SET DEVICE IDENTIFIER command has been successful7h-DATA PROTECTION Code 8h-BLANK CHECK related to a missing EOD data set. The most likely cause Bh-ABORTED COMMANDREAD BUFFER command 76 Sense keys and codes Dh-VOLUME OVERFLOWA WRITE or WRITE FILEMARKS command has encountered Typical escalation procedure 1. Retrieve fault information3. Allow the user to try recovery 4. Allow the user to reset devicesMonitoring the condition of the drive and media Supporting TapeAlertFlags TypePage Page Page Page Page Page Page Designing software to use the TapeAlert log TapeAlert modelsTapeAlert informational exception usage model Reading the TapeAlert logTapeAlert polling usage model Supporting OBDR One-Button Disaster Recovery OBDRResponding to the ‘Clean’ LED Providing pass-through mode Requirements for drivers and logical device managersGlossary see ”read-while-write” Index Page Page HP restricted