Seagate ST1000NM0041 manual Background Media Scan, Media Pre-Scan, Deferred Auto-Reallocation

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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 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 or reallocated per ARRE/AWRE settings.

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 first BMS scan for a newly manufactured drive is performed as quickly as possible to verify the media and protect data by setting the “Start time after idle” to 5ms, all subsequent scans begin after 500ms of idle time. Other features that normally use idle time to function will function normally because BMS functions for bursts of 800ms 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 1 ms.

10.5Media Pre-Scan

Media Pre-Scan is a feature that allows the drive to repair media errors that would otherwise have been found by the host system during critical data accesses early in the drive’s life. The default setting for Media Pre-Scan is enabled on standard products. Media Pre-Scan checks each write command to determine if the destination LBAs have been scanned by BMS. If the LBAs have been verified, the drive proceeds with the normal write command. If the LBAs have not been verified by BMS, Pre-Scan will convert the write to a write verify to certify that the data was properly written to the disk.

Note. During Pre-Scan write verify commands, write performance may decrease by 50% until Pre-Scan completes. Write performance testing should be performed after Pre-Scan is complete. This may be checked by reading the BMS status.

To expedite the scan of the full pack and subsequently exit from the Pre-Scan period, BMS will begin scanning immediately when the drive goes to idle during the Pre-Scan period. In the event that the drive is in a high transaction traffic environment and is unable to complete a BMS scan within 24 power on hours BMS will dis- able Pre-Scan to restore full performance to the system.

10.6Deferred Auto-Reallocation

Deferred Auto-Reallocation (DAR) simplifies reallocation algorithms at the system level by allowing the drive to reallocate unreadable locations on a subsequent write command. Sites are marked for DAR during read oper- 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.

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Constellation ES.1 SAS Product Manual, Rev. E

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Contents SED Fips 140-2 Models ST2000NM0041 ST1000NM0041 ST500NM0041Standard Models Self-Encrypting Drive Models Revision history Contents Defect and error management InstallationAbout Fips About self-encrypting drives Interface requirementsPage Constellation ES.1 SAS Product Manual, Rev. E List of Figures Constellation ES.1 SAS Product Manual, Rev. E Seagate Technology support services Seagate Online Support and ServicesScope Model Number Self-Encrypting Drive SED Fips 140-2 LevelApplicable standards and reference documentation StandardsElectromagnetic compatibility Electromagnetic susceptibilityElectromagnetic compliance Electromagnetic compliance for the European UnionAustralian C-Tick Korean KCCEuropean Union Restriction of Hazardous Substances RoHS China Restriction of Hazardous Substances RoHS DirectiveReference documents Self-Encrypting Drives Reference ManualGeneral description Performance Standard featuresMedia description Factory-installed options ReliabilityFormatted capacities Programmable drive capacityPerformance characteristics Internal drive characteristicsSeek performance characteristics Access timeGeneral performance characteristics Start/stop timePrefetch/multi-segmented cache control Cache operationCaching write data Prefetch operationReliability specifications Error ratesRecoverable Errors Unrecoverable ErrorsReliability and service Seek errorsInterface errors Preventive maintenance4 S.M.A.R.T Controlling S.M.A.R.TPerformance impact Reporting controlThermal monitor Temperature Log Page 0Dh Parameter Code DescriptionPredictive failures State of the drive prior to testing Drive Self Test DSTDST failure definition ImplementationShort and extended tests Short test Function Code 001bExtended test Function Code 010b Log page entriesProduct warranty ShippingStorage Product repair and return informationPowerChoice modes Physical/electrical specificationsPowerChoiceTM power management AC power requirements DC power requirementsRegulation ±5% Constellation ES.1 SAS Product Manual, Rev. E Constellation ES.1 SAS Product Manual, Rev. E Conducted noise immunity General DC power requirement notesPower sequencing Current profiles TB model current profilesConstellation ES.1 SAS Product Manual, Rev. E GB model current profiles Power dissipation 2TB models in 3Gb operation2TB models in 6Gb operation 1TB models in 3Gb operation 1TB models in 6Gb operation 500GB models in 3Gb operation 500GB models in 6Gb operation Relative humidity Temperature a. OperatingEnvironmental limits Shock Effective altitude sea level a. OperatingShock and vibration Vibration a. Operating-normal Recommended mountingCorrosive environment Air cleanlinessAcoustics Mechanical specifications Mounting configuration dimensionsAbout Fips PurposeValidation Program Seagate Enterprise SEDExample of Fips tamper evidence labels Controlled access Admin SPAbout self-encrypting drives Data encryptionAuthenticated firmware download Random number generator RNGDrive locking Data bandsPower requirements Supported commandsSanitize Cryptographic Erase RevertSPDrive error recovery procedures Defect and error managementDrive internal defects/errors SAS system errors Deferred Auto-Reallocation Background Media ScanMedia Pre-Scan Setting and determining the current Type Level Idle Read After WriteProtection Information PI Levels of PIIdentifying a Protection Information drive Installation Drive orientationCooling Air flowDrive mounting GroundingSAS features Interface requirementsDual port support Scsi commands supported Supported commandsSupported commands Supported commands Supported commands Constellation ES.1 inquiry data Mode Sense dataInquiry data Page Mode Sense data changeable and default values for 2TB drives Mode Sense data changeable and default values for 1TB drives 3a 38 60 30 00 00 02 Miscellaneous status Miscellaneous operating features and conditionsMiscellaneous features SAS physical interface Datum B Section C C Section a a Physical characteristics Connector requirementsElectrical description Pin descriptionsSignal characteristics PowerSAS transmitters and receivers Ready LED OutSAS-2 Specification Compliance LED drive signalDifferential signals General interface characteristicsConstellation ES.1 SAS Product Manual, Rev. E Index NumericsKCC Msid Mtbf See also cooling Page Constellation ES.1 SAS Product Manual, Rev. E Page Seagate Technology LLC Americas

ST2000NM0001, ST1000NM0041, ST500NM0001, ST2000NM0021, ST1000NM0021 specifications

Seagate is a renowned leader in data storage solutions, offering a wide array of hard disk drives (HDDs) suitable for various applications. Among their product lineup, the Seagate ST2000NM0041, ST500NM0021, ST500NM0041, ST1000NM0001, and ST1000NM0021 stand out as reliable options tailored for enterprise environments and general storage needs.

The Seagate ST2000NM0041 is a 2TB 7200 RPM drive designed for high-performance workloads in data centers. One of its key features is the use of the SATA III interface, providing data transfer speeds of up to 6 Gbps, ensuring quick access to data. This model supports advanced error recovery controls and features enhanced power management capabilities, which contribute to its reliable performance and energy efficiency.

Next, the ST500NM0021 and ST500NM0041 are both 500GB drives that cater to different consumer needs. The ST500NM0021 is a 5400 RPM drive, typically used in scenarios where lower power consumption is vital, such as in compact systems or external storage configurations. Its efficient design enables quieter operation, making it ideal for environments that require minimal noise. Conversely, the ST500NM0041 operates at a speed of 7200 RPM, making it suitable for more demanding applications that require swift read and write speeds. Both models utilize Serial ATA for connectivity, ensuring compatibility with a wide range of systems.

The ST1000NM0001 and ST1000NM0021 are 1TB drives that provide versatility across different platforms. Similar to their 500GB counterparts, the ST1000NM0001 features a 7200 RPM speed, optimizing performance for applications requiring faster data processing. In contrast, the ST1000NM0021 operates at 5400 RPM, designed for users prioritizing energy efficiency over speed, like in desktop and external storage solutions. Each of these drives supports advanced technologies such as Native Command Queuing (NCQ), which enhances performance by allowing multiple commands to be executed simultaneously.

Overall, the Seagate ST series hard drives offer flexible storage options for a variety of applications. With their robust features, including varied RPM speeds, power management, and compatibility with SATA connections, these drives cater to the needs of both consumer and enterprise markets, establishing Seagate as a trusted provider in the storage arena.
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