Seagate Understanding Operational Errors and Media Scanning on Drives
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7.3SAS 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.

7.4Background 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.

7.5Media 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.

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Contents Cheetah T10 SAS Page Contents Installation Defect and error managementSeagate Technology support services Interface requirementsList of Figures Cheetah T10 SAS Product Manual, Rev. a Cheetah T10 SAS disc drive ScopeCheetah T10 SAS Product Manual, Rev. a Standards Standards, compliance and reference documentsElectromagnetic compatibility Electromagnetic susceptibilityCompliance Reference documents Cheetah T10 SAS Product Manual, Rev. a General description Standard features Media descriptionPerformance Reliability Factory-installed accessoriesFormatted capacities Programmable drive capacityUser-installed accessories Options factory installedInternal drive characteristics Performance characteristicsAccess time Seek timeFormat command execution time minutes General performance characteristicsStart/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 Hot plugging the driveControlling S.M.A.R.T Performance impactDetermining rate Reporting controlPredictive failures Thermal monitorPrimary Temperature Temperature Log Page 0DhReference Temperature Parameter Code DescriptionInvoking DST State of the drive prior to testingShort and extended tests Short test Function Code 001bAbort Product warrantyShipping Product repair and return informationCheetah T10 SAS Product Manual, Rev. a AC power requirements Physical/electrical specificationsDC power requirements ST3300555SS DC power requirementsST373355SS DC power requirements ST3146755SS DC power requirementsST3146755SS Gbit mode Amps ST373355SS Gbit mode AmpsPower sequencing General DC power requirement notesConducted noise immunity Current profilesTypical ST3300555SS drive current profiles Typical ST3146755SS drive current profiles Typical ST373355SS drive current profiles Power dissipation ST3300555SS in 3 Gbit operationST3300555SS in 1.5 Gbit operation ST3146755SS in 1.5 Gbit operation ST3146755SS in 3 Gbit operationST373355SS in 1.5 Gbit operation ST373355SS in 3 Gbit operationEnvironmental limits Temperature a. OperatingEffective altitude sea level a. Operating Relative humidityShock and vibration ShockRecommended mounting Package size Packaged/product weight Drop heightAir cleanliness Vibration a. Operating-normalCorrosive environment Acoustics Mechanical specificationsDefect and error management Drive internal defects/errorsDrive error recovery procedures Write retry count LBA cumulative, msec SAS system errors Background Media ScanMedia Pre-Scan Idle Read After Write Deferred Auto-ReallocationDrive orientation InstallationAir flow CoolingGrounding Drive mountingCheetah T10 SAS Product Manual, Rev. a Interface requirements SAS featuresDual port support Scsi commands supported Commands supported by Cheetah T10 SAS family drivesCommand name Command code Supported Commands supported by Cheetah T10 SAS family drives Commands supported by Cheetah T10 SAS family drives Commands supported by Cheetah T10 SAS family drives Inquiry data Mode Sense dataCheetah T10 SAS inquiry data Bytes Data hexPage Mode Pages ST3300555SS Mode Sense dataST3146755SS Mode Sense data ST373355SS Mode Sense data Miscellaneous features Miscellaneous operating features and conditionsSupported Feature or condition Miscellaneous statusSAS physical interface Datum B Connector requirements Physical characteristicsElectrical description Pin Signal name Signal typePin descriptions SAS pin descriptionsPower Signal characteristicsSAS transmitters and receivers Ready LED OutDifferential signals LED drive signalGeneral interface characteristics Eye masks Eye masks overviewJitter tolerance masks Receive eye maskAbsolute amplitude Normalized time in UISinusoidal Peak-toJitter Frequency in kHzSignal characteristica Units Gbps Transmitter signal characteristicsSignal characteristic Units Gbps Receiver signal characteristicsMaximum allowable jitter Gbps m, n Deterministic jitterqReceiver jitter tolerance Impedance specificationsCompliant jitter test pattern Cjtpat Impedance requirements Sheet 1Transmitter characteristics Impedance requirements Sheet 2Electrical TxRx connections = -5,437dB Shows the zero-length test load Receiver characteristics Cheetah T10 SAS Product Manual, Rev. a Warranty Service Seagate Technology support servicesInternet MySeagate Spp.seagate.com Presales SupportData Recovery Services Data Recovery Services Authorized Service CentersFAX services-All Europe toll call Call center Presales and Technical Support Warranty ServiceToll-free support numbers Africa/Middle East support services Numerics IndexPage SAS See also cooling Page Seagate Technology LLC

ST3300555SS, ST3146755SS, ST373355SS specifications

The Seagate ST373355SS, ST3146755SS, and ST3300555SS represent a range of high-performance hard drives designed for enterprise applications, particularly in server environments requiring reliability, speed, and high capacity.

The ST373355SS is a 73.5 GB SCSI hard drive operating at 15,000 RPM, which ensures rapid data access and superior performance, making it ideal for transactional applications and data-intensive tasks. With its 4 MB cache, the drive leverages fast read and write speeds, enhancing overall system responsiveness. The SCSI interface, operating at 80 MB/s, allows for high-speed data transfers, making it a suitable choice for demanding environments where quick access to information is critical. Its hot-swappable feature enables maintenance without shutting down the system, maximizing uptime and productivity.

The ST3146755SS, with a capacity of 146.8 GB, builds on the performance of its predecessor while introducing improvements in data handling and reliability. Operating at the same impressive 15,000 RPM, this model also features a 16 MB cache that greatly improves data throughput and access speed. The drive is designed to reduce latency, which is crucial for applications where timing is everything. It is equipped with advanced error recovery features and Seagate’s innovative PowerTrim technology, which improves power efficiency during read and write operations. The ST3146755SS also features a higher mean time between failures (MTBF), underscoring its reliability in high-demand environments.

Lastly, the ST3300555SS offers even greater capacity with 300 GB. This drive maintains the 15,000 RPM rotation speed and benefits from a 16 MB cache, providing a balance of speed and storage capacity. Its advanced SCSI interface supports not just speed but also data integrity, ensuring consistent performance during extensive data transfers. The drive is designed to handle workloads naturally associated with enterprise servers, data warehouses, and video editing applications. Its rugged build supports continuous operation and is tested for high-temperature environments to ensure durability.

In summary, the Seagate ST373355SS, ST3146755SS, and ST3300555SS hard drives are engineered for enterprise environments, combining impressive RPM speeds, significant storage capacities, and advanced technologies to deliver reliability, performance, and efficiency for critical applications. These hard drives represent Seagate's commitment to providing solutions that meet the rigorous demands of modern data environments.
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