Seagate ST9450404SS, ST9600204SS Idle Read After Write, Protection Information PI, Levels of PI

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10.7Idle 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.

10.8Protection Information (PI)

Protection Information is intended as a standardized approach to system level LRC traditionally provided by systems using 520 byte formatted LBAs. Drives formatted with PI information provide the same, common LBA count (i.e. same capacity point) as non-PI formatted drives. Sequential performance of a PI drive will be reduced by approximately 1.56% due to the extra overhead of PI being transferred from the media that is not calculated as part of the data transferred to the host. To determine the full transfer rate of a PI drive, transfers should be calculated by adding the 8 extra bytes of PI to the transferred LBA length, i.e. 512 + 8 = 520. PI for- matted drives are physically formatted to 520 byte sectors that store 512 bytes of customer data with 8 bytes of Protection Information appended to it. The advantage of PI is that the Protection Information bits can be man- aged at the HBA and HBA driver level. Allowing a system that typically does not support 520 LBA formats to integrate this level of protection.

Protection Information is valid with any supported LBA size. 512 LBA size is used here as common example.

10.8.1Levels of PI

There are 4 types of Protection Information.

Type 0 - Describes a drive that is not formatted with PI information bytes. This allows for legacy support in non- PI systems.

Type 1 - Provides support of PI protection using 10 and 16 byte commands. The RDPROTECT and WRTPRO- TECT bits allow for checking control through the CDB. Eight bytes of Protection Information are transmitted at LBA boundaries across the interface if RDPROTECT and WRTPROTECT bits are nonzero values. Type 1 does not allow the use of 32 byte commands.

Type 2 - Provides checking control and additional expected fields within the 32 byte CDBs. Eight bytes of Pro- tection Information are transmitted at LBA boundaries across the interface if RDPROTECT and WRTPRO- TECT bits are nonzero values. Type 2 does allow the use of 10 and 16 byte commands with zero values in the RDPROTECT and WRTPROTECT fields. The drive will generate 8 bytes (e.g.0xFFFF) 8 bytes of Protection Information to be stored on the media, but the 8 bytes will not be transferred to the host during a read com- mand.

Type 3 - Seagate products do not support Type 3.

10.8.2Setting and determining the current Type Level

A drive is initialized to a type of PI by using the format command on a PI capable drive. Once a drive is format- ted to a PI Type, it may be queried by a Read Capacity (16) command to report the PI type which it is currently formatted to. PI Types cannot coexist on a single drive. A drive can only be formatted to a single PI Type. It can be changed at anytime to a new Type but requires a low level format which destroys all existing data on the drive. No other vehicle for changing the PI type is provided by the T10 SBC3 specification.

Type 1

PI format CDB command: 04

90 00 00 00 00,

Write Buffer: 00 A0 00 00

Type 2

PI format CDB command: 04

D0 00 00 00 00,

Write Buffer: 00 A0 00 00

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Contents ST9600004SS ST9450204SS ST9600204SSST9600104SS ST9450404SSST9450304SSStandard Models Self-Encrypting Drive Models SED Fips 140-2 ModelsRevision history Contents Installation Defect and error managementAbout Fips About self-encrypting drives Interface requirementsPage Savvio 10K.4 SAS Product Manual, Rev. E 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 documentsGeneral description Media description Standard featuresReliability PerformanceFormatted capacities Programmable drive capacityFactory-installed options Internal drive characteristics Performance characteristicsSeek performance characteristics Access timeStart/stop time General performance characteristicsCaching write data Prefetch/multi-segmented cache controlCache operation Prefetch operation Error rates Reliability specificationsRecoverable Errors Unrecoverable ErrorsSeek errors Reliability and serviceInterface errors Preventive maintenanceControlling S.M.A.R.T 4 S.M.A.R.TPerformance impact Reporting controlThermal monitor Temperature Log Page 0Dh Parameter Code DescriptionPredictive failures 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 entriesProduct repair and return information Product warrantyShipping PowerChoice modes Physical/electrical specificationsPowerChoiceTM power management DC power requirements AC power requirementsPage 450GB standard model DC power requirements 0Gb mode Amps Conducted noise immunity General DC power requirement notesPower sequencing Current profiles for 600GB models Current profilesCurrent profiles for 450GB models GB models in 3Gb operation Power dissipation600GB models in 6Gb operation 450GB models in 3Gb operation 450GB models in 6Gb operation Temperature a. OperatingEnvironmental limits Shock and vibration Relative humidityEffective altitude sea level a. Operating Shock Recommended mounting Corrosive environment Air cleanlinessVibration a. Operating-normal Acoustics Mounting configuration dimensions Mechanical specificationsLevel 2 security About FipsPurpose Admin SP Controlled accessAbout self-encrypting drives Data encryptionRandom number generator RNG Default passwordDrive locking Data bandsPower requirements Authenticated firmware downloadSupported commands Cryptographic eraseDrive error recovery procedures Defect and error managementDrive internal defects/errors SAS system errors Deferred Auto-Reallocation Background Media ScanMedia Pre-Scan Idle Read After Write Setting and determining the current Type LevelProtection Information PI Levels of PIIdentifying a Protection Information drive Drive orientation InstallationAir flow CoolingGrounding Drive mountingInterface requirements SAS featuresDual port support Supported commands Scsi commands supportedSupported commands Supported commands Supported commands Savvio inquiry data Mode Sense dataInquiry data Page Mode Pages Mode Sense data for 600GB drivesMode Sense values for 450GB drives Miscellaneous status Miscellaneous operating features and conditionsMiscellaneous features 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 IndexKCC Msid Mtbf See also cooling Page Savvio 10K.4 SAS Product Manual, Rev. E Page Seagate Technology LLC
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