Seagate ST31000640SSIM manual 108.29

Page 42

The drive firmware error recovery algorithms consists of 11 levels for read recoveries and five levels for write. Each level may consist of multiple steps, where a step is defined as a recovery function involving a single re- read or re-write attempt. The maximum level used by the drive in LBA recovery is determined by the read and write retry counts.

Table 5 equates the read and write retry count with the maximum possible recovery time for read and write recovery of individual LBAs. The times given do not include time taken to perform reallocations. Reallocations are performed when the ARRE bit (for reads) or AWRE bit (for writes) is one, the RC bit is zero, and the recov- ery time limit for the command has not yet been met. Time needed to perform reallocation is not counted against the recovery time limit.

When the RC bit is one, reallocations are disabled even if the ARRE or AWRE bits are one. The drive will still perform data recovery actions within the limits defined by the Read Retry Count, Write Retry Count, and Recovery Time Limit parameters. However, the drive does not report any unrecovered errors.

Table 5: Read and write retry count maximum recovery times

Read retry count1

Maximum recovery time per

LBA (cumulative, msec)

 

 

0

108.29

 

 

1

124.95

 

 

2

424.83

 

 

3

483.14

 

 

4

583.78

 

 

5

646.11

 

 

6

712.75

 

 

7

870.69

 

 

8

964.71

 

 

9

1031.35

 

 

10

1089.66

 

 

11 (default)

2369.00

 

 

Write retry count1

Maximum recovery time per

LBA (cumulative, msec)

 

 

0

49.98

 

 

1

74.97

 

 

2

116.62

 

 

3

141.61

 

 

4

250.08

 

 

5 (default)

308.39

 

 

[1]These values are subject to change.

Setting these retry counts to a value below the default setting could result in degradation of the unrecov- ered error rate which may exceed the value given in this product manual. A setting of zero (0) will result in the drive not performing error recovery.

For example, suppose the read/write recovery page has the RC bit set to 0, read retry count set to 4, and the recovery time limit field (Mode Sense page 01, bytes 10 and 11) set to FF FF hex (maximum). A four LBA Read command is allowed to take up to 297.38 msec recovery time for each of the four LBAs in the command. If the recovery time limit is set to 00 C8 hex (200 msec decimal) a four LBA read command is allowed to take up to 200 msec for all error recovery within that command. The use of the Recovery Time Limit field allows finer granularity on control of the time spent in error recovery. The recovery time limit only starts counting when the drive is executing error recovery and it restarts on each command. There- fore, each command’s total recovery time is subject to the recovery time limit. Note: A recovery time limit of 0 will use the drive’s default value of FF FF. Minimum recovery time limit is achieved by setting the Recovery Time Limit field to 00 01.

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Barracuda ES.2 SAS Product Manual, Rev. G

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Contents Barracuda ES.2 SAS ST31000640SS ST3750630SS ST3500620SSPage Physical/electrical specifications Performance characteristicsReliability specifications General descriptionDefect and error management InstallationInterface requirements Seagate Technology Support Services Barracuda ES.2 SAS Product Manual, Rev Scope Barracuda ES.2 SAS Product Manual, Rev. G Electromagnetic compatibility Standards, compliance and reference documentsStandards Electromagnetic susceptibilityCompliance Reference documents Barracuda ES.2 SAS Product Manual, Rev. G General description Barracuda ES.2 drive illustrationPerformance Standard featuresMedia description ReliabilityFactory-installed options Formatted capacitiesProgrammable drive capacity Barracuda ES.2 SAS Product Manual, Rev. G Access time Performance characteristicsInternal drive characteristics Seek performanceFormat command execution time minutes General performance characteristicsStart/stop time Prefetch/multi-segmented cache control Cache operationCaching write data Prefetch operation Recoverable Errors Reliability specificationsError rates Unrecoverable ErrorsInterface errors Reliability and serviceSeek errors Preventive maintenancePerformance impact 4 S.M.A.R.TControlling S.M.A.R.T Reporting controlTemperature Log Page 0Dh Predictive failuresThermal monitor Implementation State of the drive prior to testingDST failure definition Invoking DSTExtended test Function Code 010b Product warrantyShort test Function Code 001b Log page entriesShipping Product repair and return informationBarracuda ES.2 SAS Product Manual, Rev. G DC power requirements Physical/electrical specificationsAC power requirements ST31000640SS DC power requirementsST3750630SS DC power requirements ST3500620SS DC power requirementsConducted noise immunity General DC power requirement notesPower sequencing Current profilesTypical ST31000640SS drive +5V and +12V current profiles Power dissipation Typical ST3500620SS drive +5V and +12V current profilesBarracuda ES.2 SAS Product Manual, Rev. G Temperature a. Operating Environmental limitsShock and vibration Relative humidityEffective altitude sea level a. Operating ShockPackage size Packaged/product weight Drop height Acoustics Air cleanlinessVibration a. Operating-normal Corrosive environmentSee Section Barracuda ES.2 SAS Product Manual, Rev. G Mechanical specifications Physical dimensionsDefect and error management Drive internal defects/errorsDrive error recovery procedures 108.29 SAS system errors Background Media ScanMedia Pre-Scan Deferred Auto-Reallocation Idle Read After WriteInstallation Drive orientationCooling Air flowDrive mounting GroundingBarracuda ES.2 SAS Product Manual, Rev. G SAS features Interface requirementsDual port support Scsi commands supported Commands supported by Barracuda ES.2 SAS family drivesCommand name Command code Supported Commands supported by Barracuda ES.2 SAS family drives Commands supported by Barracuda ES.2 SAS family drives Commands supported by Barracuda ES.2 SAS family drives Mode Sense data Inquiry dataBarracuda ES.2 SAS inquiry data Bytes Data hex Page 2.1 ST31000640SS Mode Sense data Mode Pages2.2 ST3750630SS Mode Sense data 2.3 ST3500620SS Mode Sense data Supported Feature or condition Miscellaneous operating features and conditionsMiscellaneous features Miscellaneous statusSAS physical interface Datum B Physical characteristics Connector requirementsPin descriptions Pin Signal name Signal typeElectrical description SAS pin descriptionsSAS transmitters and receivers Signal characteristicsPower Ready LED OutGeneral interface characteristics LED drive signalDifferential signals Eye masks Eye masks overviewAbsolute amplitude Receive eye maskJitter tolerance masks Normalized time in UIJitter Peak-toSinusoidal Frequency in kHzTransmitter signal characteristics Signal characteristica Units GbpsMaximum allowable jitter Receiver signal characteristicsSignal characteristic Units Gbps Gbps m, n Deterministic jitterqCompliant jitter test pattern Cjtpat Impedance specificationsReceiver jitter tolerance Impedance requirements Sheet 1Transmitter characteristics Impedance requirements Sheet 2Electrical TxRx connections = -5,437dB Shows the zero-length test load Receiver characteristics Barracuda ES.2 SAS Product Manual, Rev. G
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