Seagate ST3450802SS, ST3600002SS manual Idle Read After Write

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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.

8.7Idle 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.

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Cheetah NS 10K.2 SAS Product Manual, Rev. F

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Contents Cheetah NS 10K.2 SAS ST3600002SS ST3450802SSPage Contents Interface requirements Defect and error managementInstallation Seagate Technology support services Seagate Online Support and ServicesScope Electromagnetic compatibility Standards, compliance and reference documentsStandards Electromagnetic susceptibilityCompliance Reference documents General description Performance Standard featuresMedia description ReliabilityProgrammable drive capacity Factory-installed optionsFormatted capacities Access time Performance characteristicsInternal drive characteristics Seek performanceStart/stop time Format command execution time minutesGeneral performance characteristics Caching write data Prefetch/multi-segmented cache controlCache operation Prefetch operation Recoverable Errors Reliability specificationsError rates Unrecoverable ErrorsPreventive maintenance Reliability and serviceInterface errors Hot plugging the drivePerformance impact 4 S.M.A.R.TControlling S.M.A.R.T Reporting controlThermal monitor Temperature Log Page 0Dh Parameter Code DescriptionPredictive failures Drive Self Test DSTDST failure definition ImplementationExtended test Function Code 010b Product warrantyShort test Function Code 001b Shipping DC power requirements Physical/electrical specificationsAC power requirements ST3600002SS DC power requirementsST3450802SS DC power requirements General DC power requirement notesCurrent profiles Power sequencingConducted noise immunity Typical ST3600002SS drive +5V and +12V current profiles ST3450802SS Power dissipationST3600002SS Temperature a. Operating Environmental limitsShock and vibration Relative humidityEffective altitude sea level a. Operating ShockRecommended mounting Acoustics Air cleanlinessVibration a. Operating-normal Corrosive environmentChina Restriction of Hazardous Substances RoHS Directive Mechanical specifications Physical dimensionsDrive error recovery procedures Defect and error managementDrive internal defects/errors 77.81 Media Pre-Scan SAS system errorsBackground Media Scan Deferred Auto-ReallocationIdle Read After Write Installation Drive orientationCooling Air flowDrive mounting GroundingSAS features Interface requirementsDual port support Scsi commands supported Commands supported by Cheetah NS 10K.2 SAS family drivesCommands supported by Cheetah NS 10K.2 SAS family drives Commands supported by Cheetah NS 10K.2 SAS family drives Commands supported by Cheetah NS 10K.2 SAS family drives Inquiry data 10.3.2Mode Sense dataPage 10.3.2.1 ST3600002SS Mode Sense data Mode Pages10.3.2.2 ST3450802SS Mode Sense data Miscellaneous status Miscellaneous operating features and conditionsMiscellaneous features SAS physical interface Datum B Physical characteristics Connector requirementsSAS pin descriptions Electrical descriptionPin descriptions SAS transmitters and receivers Signal characteristicsPower Ready LED OutGeneral interface characteristics LED drive signalDifferential signals 10.5.2.1 Eye masks 10.5.2.1.1 Eye masks overviewReceive eye mask 2OP 0, 5 xadditional sinusoidal jitter X 1OP Transmitter signal characteristics Receiver signal characteristics Maximum allowable jitterCompliant jitter test pattern Cjtpat Impedance requirements Sheet 1Impedance requirements Sheet 2 Electrical TxRx connections= -5, 437dB Shows the zero-length test load Additional information SAS-2 Specification complianceReceiver characteristics Cheetah NS 10K.2 SAS Product Manual, Rev. F Index Page SAS See also cooling Page Seagate Technology LLC Americas
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