Seagate ST400FX0002 Drive error recovery procedures, SAS system errors, Background Media Scan

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The DIE field contains the die number within channel.

The BLOCK field contains the block number within the die.

The VENDOR UNIQUE field may contain vendor unique information.

9.2Drive error recovery procedures

When an error occurs during drive operation, the drive performs error recovery procedures to attempt to recover the data. The error recovery procedures used are not user changeable.

9.3SAS system errors

Information on the reporting of operational errors across the interface is given in the SAS Interface Manual. The SSP Response returns information to the host about numerous kinds of errors. 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.

9.4Background 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 reads across the entire addressable space 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 service by the host system. On regular duty drives, if the host system makes use of the BMS Log Page, it can avoid placing data in suspect locations on the media. Unreadable and recovered error sites will be logged and reallocated.

With BMS, the host system can consume less power and system overhead by only checking BMS status and results rather than tying up the bus and consuming power in the process of host-initiated media scanning activ- ity.

Since the background scan functions are only done during idle periods, BMS causes a negligible impact to sys- tem performance. The BMS scan is performed after 500ms of idle time. Other features that normally use idle time to function will function normally because BMS functions for bursts of 500ms and then suspends activity for 100ms to allow other background functions to operate.

BMS interrupts immediately to service host commands from the interface bus while performing reads. BMS will complete any BMS-initiated error recovery prior to returning to service host-initiated commands. Overhead associated with a return to host-servicing activity from BMS only impacts the first command that interrupted BMS, this results in a typical delay of about 1ms.

9.5Auto-Reallocation

Auto-Reallocation allows the drive to reallocate unreadable locations on a subsequent write command if the recovery process deems the location to be defective. The drive performs auto-reallocation on every WRITE command. With each write to a Logical LBA, the drive writes the data to a different physical media location. Physical locations that return unrecoverable errors are retired during future WRITE attempts and associated recovery process.

This is in contrast to the system having to use the REASSIGN BLOCKS command to reassign a location that was unreadable and then generate a WRITE command to rewrite the data. This operation requires that AWRE and ARRE are enabled—this is the default setting from the Seagate factory.

Pulsar XT.2 SAS Product Manual, Rev. B

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Contents Standard Models Self-Encrypting Drive Models ST400FX0002ST400FX0012 ST200FX0002 ST100FX0002Revision history Contents About self-encrypting drives Physical/electrical specificationsDefect and error management InstallationPage Pulsar XT.2 SAS Product Manual, Rev. B List of Figures Page Seagate Online Support and Services Seagate Technology support servicesScope Electromagnetic susceptibility Applicable standards and reference documentationStandards Electromagnetic compatibilityKorean KCC Electromagnetic complianceElectromagnetic compliance for the European Union Australian C-TickChina Restriction of Hazardous Substances RoHS Directive Reference documentsGeneral description Standard featuresReliability Media descriptionPerformance Programmable drive capacity Factory-installed optionsFormatted capacities Thin Provisioning Drive Configuration Access time Performance characteristicsInternal drive characteristics Performance characteristicsPerformance Format Mode Dcrt Bit IP Bit 400GB 200GB 100GBCaching write data Start/stop timeCache control Error rates Reliability specificationsEndurance Management Lifetime Endurance Management Reliability and servicePreventive maintenance Data RetentionPerformance impact Maximum processing delay Fully-enabled delay4 S.M.A.R.T Controlling S.M.A.R.TThermal monitor Predictive failuresImplementation State of the drive prior to testingDrive Self Test DST DST failure definitionLog page entries Short and extended testsShort test Function Code 001b Extended test Function Code 010bStorage Product warrantyShipping Product repair and return informationAC power requirements Physical/electrical specificationsPower specifications 400GB standard model DC power requirements DC power requirements200GB standard model DC power requirements 100GB standard model DC power requirements Current profiles General DC power requirement notesPower sequencing Conducted noise immunityCurrent profiles for 200GB models 200GB models in 6Gb operation Power dissipation400GB models in 6Gb operation 100GB models in 6Gb operation Temperature a. OperatingEnvironmental limits Shock and vibration Relative humidityEffective altitude sea level a. Operating Recommended mounting ShockCorrosive environment Air cleanlinessVibration a. Operating-normal Mounting configuration dimensions 400GB models Mechanical specificationsWeight Pounds 100 grams Data encryption Controlled accessAdmin SP About self-encrypting drivesData bands Default passwordRandom number generator RNG Drive lockingCryptographic erase Authenticated firmware downloadPower requirements Supported commandsSSD Physical format address descriptor Bit Byte Defect and error managementDrive internal defects/errors Auto-Reallocation Drive error recovery proceduresSAS system errors Background Media ScanIdentifying a Protection Information drive Setting and determining the current Type LevelProtection Information PI Levels of PIDrive orientation InstallationAir flow CoolingGrounding Drive mountingInterface requirements SAS featuresDual port support Supported commands Scsi commands supportedPersistent Reserve Read Capacity Write Inquiry data Mode Sense dataPage 14 1a 00 1a Mode Sense data for 400GB drivesMode Pages Mode Sense data for 200GB drivesMode Sense values for 100GB drives SAS physical interface Miscellaneous operating features and conditionsMiscellaneous features Miscellaneous statusDatum B Section C C Section a a Pin descriptions Physical characteristicsConnector requirements Electrical descriptionReady LED Out Signal characteristicsPower SAS transmitters and receiversGeneral interface characteristics SAS-2 Specification complianceLED drive signal Differential signalsNumerics IndexPage RNG See also cooling Page Americas Seagate Technology LLC
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