Seagate ST3300655FC, ST373455FC Media Pre-Scan, Deferred Auto-Reallocation, Idle Read After Write

Page 52

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.

7.6Deferred 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.

7.7Idle 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.

42

Cheetah 15K.5 FC Product Manual, Rev. D

Page 51 Page 53
Image 52
Page 51 Page 53
Contents Cheetah 15K.5 FC Page Cheetah 15K.5 FC Product Manual, Rev. D Cheetah 15K.5 FC Product Manual, Rev. D Contents Installation Defect and error managementInterface requirements Seagate Technology support services Cheetah 15K.5 FC Product Manual, Rev. D List of Figures Page Scope Cheetah 15K.5 FC Product Manual, Rev. D Applicable standards and reference documentation StandardsElectromagnetic compatibility Electromagnetic susceptibilityEuropean Union Restriction of Hazardous Substances RoHS Reference documents Ncits TR-20Cheetah 15K.5 FC Product Manual, Rev. D General description Standard features Media descriptionPerformance ReliabilityFormatted capacities Programmable drive capacityFactory-installed options Factory-installed accessoriesUser-installed accessories Performance characteristics Internal drive characteristicsSeek performance characteristics Access timeFormat command execution time minutes General performance characteristicsStart/stop time Prefetch/multi-segmented cache controlCache operation Caching write dataPrefetch operation Reliability 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 MillisecondsReporting control Determining ratePredictive failures Thermal monitorState of the drive prior to testing Parameter Code DescriptionDrive Self Test DST DST failure definitionInvoking DST Short and extended testsShort test Function Code 001b Extended test Function Code 010bProduct warranty AbortShipping Product repair and return informationCheetah 15K.5 FC Product Manual, Rev. D Physical/electrical specifications AC power requirementsDC power requirements DC power requirements for ST3300655FC model Gbit AmpsDC power requirements for ST3146855FC model Gbit Amps DC power requirements for ST373455FC model Gbit AmpsGeneral DC power requirement notes Power sequencingConducted noise immunity Current profilesTypical ST3300655FC drive, 4 Gbit, +12V current profile Typical ST3146855FC drive, 4 Gbit, +12V current profile Typical ST373455FC drive, 4 Gbit, +12V current profile Power dissipation ST3300655FCST3146855FC CURRENT/POWER vs Throughput FC 4GB ST3146855FCTemperature ST373455FC CURRENT/POWER vs Throughput FC 4GBEnvironmental limits ST373455FCRelative humidity Effective altitude sea levelShock and vibration ShockPackage size Packaged/product weight Drop height Recommended mounting Air cleanliness VibrationAcoustics Corrosive environmentRoHS compliance statement Mechanical specifications Mounting configuration dimensionsCheetah 15K.5 FC Product Manual, Rev. D Drive internal defects/errors Defect and error managementDrive error recovery procedures Page FC-AL system errors Background Media ScanDeferred Auto-Reallocation Media Pre-ScanIdle Read After Write Installation Drive ID/option selectionDrive orientation CoolingDrive mounting Air flowGrounding Cheetah 15K.5 FC Product Manual, Rev. D FC-AL features Fibre Channel link service framesLink services supported Type of frame Interface requirementsFibre Channel task management responses Fibre Channel task management functionsFC Scsi FCP response codes Function name Response code Fibre Channel port login NPort login Plogi payload BytesFibre Channel port login accept Fibre Channel Process LoginNPort Login Accept ACC payload Bytes Process Login Plri payloadFibre Channel Process Login Accept Fibre Channel fabric loginProcess Login Accept ACC payload Bytes Fabric Login Flogi payload BytesFibre Channel fabric accept login Fabric Login Accept ACC payload BytesDual port support Fibre Channel Arbitrated Loop optionsFC-AL options supported Option SupportedScsi commands supported Supported commands Command code Command nameVerify error recovery page 07h Cheetah 15K.5 FC Product Manual, Rev. D Temperature page 0Dh Inquiry data Mode Sense dataCheetah 15K.5 FC inquiry data Bytes Data hex Page Mmode Sense 10 Byte Header Data Mode Sense 10 Byte Header Data 00 ae 00 10 00 00 00 08 08 8b b9 98 00 00 02 Miscellaneous operating features and conditions Miscellaneous featuresSupported Feature or condition Miscellaneous statusFC-AL physical interface Physical characteristicsPhysical description Electrical description Connector requirementsPin descriptions Pin Signal name Signal type FC-SCA pin descriptions Pin Signal name Signal typeFC-AL transmitters and receivers Power Fault LED OutActive LED Out Enable port bypass signalsMotor start controls Parallel Enclosure Services Interface ESI 11 SEL6 through SEL0 ID linesArbitrated loop physical address Alpa values SettingHex Dec TTL input characteristics Signal characteristicsDevice control codes FC Differential output LED driver signalsFC Differential input Receive eye diagram Eye diagram data values Link rate GHz Cheetah 15K.5 FC Product Manual, Rev. D Seagate Technology support services Warranty ServiceInternet MySeagate Spp.seagate.com Presales SupportData Recovery Services Authorized Service Centers Data Recovery ServicesCall center Presales and Technical Support Warranty Service FAX services-All Europe toll callToll-free support numbers Asia/Pacific support services Index NumericsFAN Flogi Plogi Page See also cooling

ST3146855FC, ST373455FC, ST3300655FC specifications

Seagate is renowned for its commitment to high-performance data storage solutions, and their range of enterprise drives, including the ST3300655FC, ST373455FC, and ST3146855FC, demonstrates this dedication. These models cater to businesses requiring robust, reliable, and efficient hard disk drives (HDDs) designed for demanding environments.

The ST3300655FC offers a capacity of 300 GB, making it suitable for a variety of enterprise applications. It utilizes a 15,000 RPM spindle speed, which significantly enhances its performance, delivering quick read and write times. This drive supports Serial Attached SCSI (SAS) interface, ensuring faster data transfer rates and reliability essential for critical computing environments. The dual-port connectivity of SAS allows for enhanced fault tolerance and redundancy, making the ST3300655FC ideal for data centers and enterprise storage systems.

Following closely, the ST373455FC provides a slightly larger capacity of 734 GB while maintaining the same 15,000 RPM speed. This drive's design focuses on high availability, making it an excellent choice for applications that require continuous uptime. Like its counterpart, it also benefits from the SAS interface, ensuring that data can be accessed quickly and reliably. The robust construction of the ST373455FC guarantees consistent performance under heavy workloads, an essential characteristic for enterprise use.

The ST3146855FC, with a capacity of 146 GB, offers a balance between speed and storage for enterprises that do not require the larger capacities provided by the other two models. It also operates at 15,000 RPM, benefiting from similar technological advancements as the ST3300655FC and ST373455FC. This drive maintains compatibility with existing systems, making it a versatile option for organizations looking to upgrade their storage solutions without overhauling their infrastructure.

All three models exhibit Seagate's commitment to durability and low power consumption, which is critical for reducing operational costs in data centers. They also feature advanced error recovery and data integrity technologies, ensuring that critical data remains intact and accessible. Enhanced thermal and vibration tolerance further extends the lifespan of these drives in challenging environments.

In summary, the Seagate ST3300655FC, ST373455FC, and ST3146855FC are tailored to meet the rigorous demands of enterprise environments. Their high spindle speeds, SAS connectivity, and robust designs make them exemplary choices for businesses seeking reliable and efficient storage solutions. Their distinctive features and technologies ensure that they deliver outstanding performance, data integrity, and durability, making them invaluable assets in any data-driven organization.
Top Page Image Contents