Seagate ST9300553SS, ST9300653SS, ST9300453SS, ST9146753SS SAS system errors, Background Media Scan

Page 49

The drive firmware error recovery algorithms consists of 20 levels for read recoveries and six 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 4 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 4: Read and write retry count maximum recovery times

 

Maximum recovery time per

Read retry count*

LBA (cumulative, ms)

 

 

 

 

1

124.32

 

 

5

621.62

 

 

10

1243.23

 

 

15

1864.85

 

 

20 (default)

2486.47

 

 

Write retry count

Maximum recovery time per

LBA (cumulative, ms)

 

 

0

35.94

 

 

1

53.91

 

 

2

79.89

 

 

3

97.86

 

 

4

175.85

 

 

5 (default)

421.79

 

 

*For read retry count, every tick ~ 5% of total error recovery. Valid range setting is 1-20. e.g. 1 ~ 5%

5 ~ 25%

20 ~ 100%

Settingthese retry counts to a value below the default setting could result in degradation of the unrecovered error rate. For example, suppose the read/write recovery page has the RC bit = 0 and if the read retry count is set to 5, this means ~ 25% of error recovery will be executed which consumes 621.62 ms (please refer to the table above). If the limit is reached and a LBA has not yet been recovered (i.e. requires retries beyond 621.62 ms), the command will end with Check Condition status report and unrecoverable read error will be reported.

10.3SAS system errors

Information on the reporting of operational errors or faults across the interface is given in the SAS Interface Manual. The SSP Response returns information to the host about numerous kinds of errors or faults. The Receive Diagnostic Results reports the results of diagnostic operations performed by the drive.

Status returned by the drive to the initiator is described in the SAS Interface Manual. Status reporting plays a role in systems error management and its use in that respect is described in sections where the various com- mands are discussed.

10.4Background Media Scan

Background Media Scan (BMS) is a self-initiated media scan. BMS is defined in the T10 document SPC-4 available from the T10 committee. BMS performs sequential reads across the entire pack of the media while the drive is idle. In RAID arrays, BMS allows hot spare drives to be scanned for defects prior to being put into

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Contents ST9300453SS ST9146653SS ST9300653SSST9300553SS ST9146853SSST9146753SSStandard Models Self-Encrypting Drive Models SED FIPS140-2 ModelsPage Contents Installation Defect and error managementAbout Fips About self-encrypting drives Interface requirementsPage Savvio 15K.3 SAS Product Manual, Rev. a List of Figures Page Seagate Online Support and Services Seagate Technology support servicesScope Standards Applicable standards and reference documentationElectromagnetic compatibility Electromagnetic susceptibilityElectromagnetic compliance for the European Union Electromagnetic complianceAustralian C-Tick Korean KCCEuropean Union Restriction of Hazardous Substances RoHS Reference documents Scsi Commands Reference Manual SAS Interface ManualGeneral description Media description Standard featuresReliability PerformanceFormatted capacities Programmable drive capacity Factory installed optionsInternal drive characteristics Performance characteristicsSeek performance characteristics Access timeGeneral performance characteristics Format command execution timeStart/stop time Cache operation Prefetch/multi-segmented cache controlPrefetch operation Caching write dataError rates Reliability specificationsRecoverable Errors Unrecoverable ErrorsSeek errors Reliability and serviceInterface errors Preventive maintenance4 S.M.A.R.T Maximum processing delayControlling S.M.A.R.T Performance impactPredictive failures Temperature Log Page 0Dh Parameter Code DescriptionThermal monitor Drive Self Test DST State of the drive prior to testingDST failure definition ImplementationShort test Function Code 001b Short and extended testsExtended test Function Code 010b Log page entriesShipping Product warrantyProduct repair and return information StoragePowerChoiceTM power management Physical/electrical specificationsPowerChoice modes DC power requirements AC power requirementsRegulation 300GB models DC power requirements146GB models DC power requirements Power sequencing General DC power requirement notesConducted noise immunity Current profile for 300GB models Current profilesCurrent profile for 146GB models 300GB models in 6Gb operation Power dissipation300GB models in 3Gb operation 146GB models in 3Gb operation 146GB models in 6Gb operationEnvironmental limits Temperature a. OperatingRelative humidity Shock and vibration Effective altitude sea level a. OperatingShock Recommended mounting Vibration a. Operating-normalCorrosive environment Air cleanlinessAcoustics Dimensions Mechanical specificationsPurpose About FipsLevel 2 security Admin SP Controlled accessAbout self-encrypting drives Data encryptionRandom number generator RNG Default passwordDrive locking Data bandsPower requirements Authenticated firmware downloadSupported commands Cryptographic eraseDrive internal defects/errors Defect and error managementDrive error recovery procedures Background Media Scan SAS system errorsDeferred Auto-Reallocation Media Pre-ScanIdle Read After Write Protection Information PI Setting and determining the current Type LevelLevels of PI Identifying a Protection Information driveDrive orientation InstallationAir flow CoolingGrounding Drive mountingInterface requirements SAS featuresSupported commands Scsi commands supportedDual port support Supported commands Supported commands Supported commands Inquiry data Mode Sense dataSavvio inquiry data Page Mode Data Header Mode Data Header Miscellaneous features Miscellaneous operating features and conditionsMiscellaneous status SAS physical interface Datum B Section C C Section a a Connector requirements Physical characteristicsElectrical description Pin descriptionsPower Signal characteristicsSAS transmitters and receivers Ready LED OutLED drive signal SAS-2 Specification complianceDifferential signals General interface characteristicsNumerics IndexPage Msid Mtbf See also cooling Page Savvio 15K.3 SAS Product Manual, Rev. a
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