Seagate ST4000NM0023 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 disc.

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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Contents Standard Models Self-Encrypting Drive Models ST32000446SS ST31000426SS ST3500416SSSED Fips 140-2 Models Revision history Contents Interface requirements Defect and error managementInstallation About Fips About self-encrypting drivesPower Constellation ES Series SAS Product Manual, Rev. F List of Figures Constellation ES Series SAS Product Manual, Rev. F 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-TickEuropean Union Restriction of Hazardous Substances RoHS Reference documentsGeneral description Media description Standard featuresProgrammable drive capacity PerformanceReliability Formatted capacitiesFactory-installed options Access time Performance characteristicsInternal drive characteristics Seek performance characteristicsStart/stop time General performance characteristicsCache operation Prefetch/multi-segmented cache controlPrefetch operation Caching write dataUnrecoverable Errors Reliability specificationsError rates Recoverable ErrorsPreventive maintenance Reliability and serviceSeek errors Interface errorsReporting control 4 S.M.A.R.TControlling S.M.A.R.T Performance impactPredictive failures Temperature Log Page 0Dh Parameter Code DescriptionThermal monitor Implementation 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 010bShipping Product warrantyProduct repair and return information PowerChoiceTM power management Physical/electrical specificationsPowerChoice modes DC power requirements AC power requirementsRegulation ±5% Constellation ES Series SAS Product Manual, Rev. F +5V Power sequencing General DC power requirement notesConducted noise immunity TB model current profiles Current profilesConstellation ES Series SAS Product Manual, Rev. F GB model current profiles 2TB models in 3Gb operation Power dissipation2TB models in 6Gb operation 1TB models in 3Gb operation 1TB models in 6Gb operation 500GB models in 3Gb operation ST3500414SS CURRENT/POWER vs Throughput SAS 3.0GBOs per Second 500GB models in 6Gb operation Environmental limits Temperature a. OperatingRelative humidity Shock and vibration Effective altitude sea level a. OperatingShock Recommended mounting Vibration a. Operating-normalAcoustics Air cleanlinessCorrosive environment Mounting configuration dimensions Mechanical specificationsPurpose About FipsLevel 2 security Data encryption Controlled accessAdmin SP About self-encrypting drivesData bands Default passwordRandom number generator RNG Drive lockingCryptographic erase Authenticated firmware downloadPower requirements Supported commandsDrive internal defects/errors Defect and error managementDrive error recovery procedures SAS system errors Media Pre-Scan Background Media ScanDeferred Auto-Reallocation Idle Read After Write Drive orientation InstallationAir flow CoolingGrounding Drive mountingInterface requirements SAS featuresDual port support Supported commands Scsi commands supportedSupported commands Supported commands Supported commands Inquiry data Mode Sense dataConstellation ES inquiry 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 features Miscellaneous operating features and conditionsMiscellaneous status SAS physical interface Datum 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 signalsConstellation ES Series SAS Product Manual, Rev. F Numerics IndexKCC Msid Mtbf See also cooling Page Constellation ES Series SAS Product Manual, Rev. F Page Seagate Technology LLC

ST4000NM0053, ST4000NM0023, ST32000444SSIM, ST32000646NS, ST3000NM0063 specifications

Seagate is a prominent name in the storage industry, renowned for its high-performance hard disk drives (HDDs). Among its popular enterprise offerings are models like the ST2000NM0043, ST32000645NS, ST3000NM0043, ST2000NM0033, and ST2000NM0023, which cater to various data center and server needs.

The Seagate ST2000NM0043 is a 2TB 7200 RPM SATA drive designed for high availability and performance in enterprise environments. It features a 128MB cache, ensuring efficient data transfer speeds and quick access to frequently used data. This model boasts a mean time between failures (MTBF) of 1.4 million hours, emphasizing its reliability for continuous operation in demanding applications.

The ST32000645NS, offering 2TB of storage and a 7200 RPM spindle speed, is ideal for environments where large amounts of data need to be stored and accessed quickly. It supports SAS interfaces, providing enhanced data integrity and improved system performance. With its aggressive power management features, this model strikes a balance between performance and energy efficiency, making it suitable for both traditional data centers and cloud applications.

The ST3000NM0043 stands out with a capacity of 3TB, further addressing the growing need for more substantial storage solutions. Like its counterparts, it operates at 7200 RPM and is equipped with advanced caching mechanisms that help enhance overall performance. Its high durability and enterprise-grade features make it a preferred choice for storage-intensive applications.

The ST2000NM0033 focuses on delivering storage solutions for environments needing both capacity and reliability. With its 2TB capacity and 7200 RPM rotation speed, it provides an effective solution for businesses looking to balance workload and storage needs without compromising performance. This model also features Seagate's advanced technology that optimizes workflow and minimizes latency.

Lastly, the ST2000NM0023 mirrors many of the features found in its siblings, offering a 2TB capacity and optimized for high reliability and performance. With Seagate's commitment to innovating in the HDD space, features such as self-monitoring, analysis, and reporting technology (SMART) help maintain the drive's health and prevent potential failures.

In conclusion, Seagate's range of HDDs, exemplified by the ST2000NM0043, ST32000645NS, ST3000NM0043, ST2000NM0033, and ST2000NM0023, reflects a dedication to providing robust, high-capacity storage solutions. Their advanced technologies, reliability ratings, and performance features make them ideal choices for enterprise environments demanding efficiency and durability.
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