Seagate ST3300602FC, ST3450802FC, ST3600002FC Deferred Auto-Reallocation, Idle Read After Write

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7.6Deferred Auto-Reallocation

Deferred Auto-Reallocation (DAR) simplifies reallocation algorithms at the system level by allowing the drive to reallocate unreadable locations on a subsequent write command. Sites are marked for DAR during read oper- ations performed by the drive. When a write command is received for an LBA marked for DAR, the auto-reallo- cation process is invoked and attempts to rewrite the data to the original location. If a verification of this rewrite fails, the sector is re-mapped to a spare location.

This is in contrast to the system having to use the Reassign Command to reassign a location that was unread- able and then generate a write command to rewrite the data. DAR is most effective when AWRE and ARRE are enabled—this is the default setting from the Seagate factory. With AWRE and ARRE disabled DAR is unable to reallocate the failing location and will report an error sense code indicating that a write command is being attempted to a previously failing location.

7.7Idle Read After Write

Idle Read After Write (IRAW) utilizes idle time to verify the integrity of recently written data. During idle periods, no active system requests, the drive reads recently written data from the media and compares it to valid write command data resident in the drives data buffer. Any sectors that fail the comparison result in the invocation of a rewrite and auto-reallocation process. The process attempts to rewrite the data to the original location. If a verification of this rewrite fails, the sector is re-mapped to a spare location.

42	Cheetah NS 10K.2 FC Product Manual, Rev. B

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Contents Cheetah NS 10K.2 FC ST3600002FC ST3450802FC ST3300602FCPage Contents Installation Seagate Technology support services Cheetah NS 10K.2 FC Product Manual, Rev. B Scope Cheetah NS 10K.2 FC Product Manual, Rev. B Standards, compliance and reference documents StandardsElectromagnetic compatibility Electromagnetic susceptibilityCompliance Reference documents Ncits TR-19Cheetah NS 10K.2 FC Product Manual, Rev. B General description Standard features Media descriptionPerformance ReliabilityFormatted capacities Factory-installed options User-installed accessoriesProgrammable drive capacity Performance characteristics Internal drive characteristicsAccess time Seek performanceFormat command execution time minutes General performance characteristicsStart/stop time ST3600002FC ST3450802FC ST3300602FCPrefetch/multi-segmented cache control Cache operationCaching write data Prefetch operationReliability specifications Error ratesRecoverable Errors Unrecoverable ErrorsReliability and service Seek errorsInterface errors Preventive maintenanceA.R.T. delay times 4 S.M.A.R.TControlling S.M.A.R.T Performance impactReporting control Determining ratePredictive failures Thermal monitorState of the drive prior to testing Temperature Log Page 0DhDrive Self Test DST DST failure definitionInvoking DST Short and extended testsShort test Function Code 001b Extended test Function Code 010bProduct warranty AbortCheetah NS 10K.2 FC Product Manual, Rev. B Physical/electrical specifications AC power requirementsDC power requirements DC power requirements for ST3600002FC model Gbit AmpsDC power requirements for ST3450802FC model Gbit Amps General DC power requirement notes DC power requirements for ST3300602FC model Gbit AmpsPower sequencing Conducted noise immunityCurrent profiles Cheetah NS 10K.2 FC Product Manual, Rev. B Cheetah NS 10K.2 FC Product Manual, Rev. B Power dissipation ST3600002FCST3450802FC ST3300602FC Temperature a. Operating Environmental limitsRelative humidity Effective altitude sea level a. Operating Shock and vibrationShock Package size Packaged/product weight Drop height Recommended mountingAir cleanliness Vibration a. Operating-normalAcoustics Corrosive environmentChina Restriction of Hazardous Substances RoHS Directive Mechanical specifications Mounting configuration dimensionsCheetah NS 10K.2 FC Product Manual, Rev. B Defect and error management Drive internal defects/errorsDrive error recovery procedures 77.81 FC-AL system errors Background Media ScanMedia Pre-Scan Deferred Auto-Reallocation Idle Read After WriteInstallation Drive ID/option selectionDrive orientation CoolingDrive mounting Air flowGrounding Cheetah NS 10K.2 FC Product Manual, Rev. B FC-AL features Fibre Channel link service framesLink services supported Type of frame Interface requirementsFibre Channel task management functions Fibre Channel task management responsesFC Scsi FCP response codes Function name Response code Fibre Channel port login NPort login Plogi payload BytesFibre Channel port login accept Fibre Channel Process LoginNPort Login Accept ACC payload Bytes Process Login Plri payloadFibre Channel Process Login Accept Fibre Channel fabric loginProcess Login Accept ACC payload Bytes Fabric Login Flogi payload BytesFibre Channel fabric accept login Fabric Login Accept ACC payload BytesDual port support Fibre Channel Arbitrated Loop optionsFC-AL options supported Option SupportedScsi commands supported Supported commands Command code Command nameVerify error recovery page 07h Cheetah NS 10K.2 FC Product Manual, Rev. B Temperature page 0Dh Mode Sense data Inquiry dataCheetah NS 10K.2 FC inquiry data Bytes Data hex Page Mode Data Header Mode Pages 00 00 05 12 8B 00 50 Miscellaneous operating features and conditions Supported Feature or conditionPhysical characteristics FC-AL physical interfacePhysical description Connector requirements Electrical descriptionPin descriptions FC-SCA pin descriptions Pin Signal name Signal type FC-AL transmitters and receiversPower Fault LED OutEnable port bypass signals Active LED OutMotor start controls Parallel Enclosure Services Interface ESI 11 SEL6 through SEL0 ID linesAlpa SEL ID Signal characteristics TTL input characteristicsDevice control codes LED driver signals FC Differential outputFC Differential input Receive eye diagram Eye diagram data values Link rate GHz Cheetah NS 10K.2 FC Product Manual, Rev. B Seagate Technology support services Presales SupportTechnical Support Warranty Service Data Recovery Services Authorized Service CentersData Recovery Services Call Center Toll-free Direct dial Index FCP Flogi Plogi Page See also cooling Page Seagate Technology LLC