Seagate ST973402SS, ST9146802SS manual Caching write data, Prefetch operation

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Case B—A Read command requests data, and at least one requested logical block is not in any segment of the cache:

1.The drive fetches the requested logical blocks from the disc and transfers them into a segment, and then from there to the host in accordance with the Mode Select Disconnect/Reconnect parameters, page 02h.

2.If the prefetch feature is enabled, refer to section 4.5.2 for operation from this point.

Each cache segment is actually a self-contained circular buffer whose length is an integer number of logical blocks. The drive dynamically creates and removes segments based on the workload. The wrap-around capa- bility of the individual segments greatly enhances the cache’s overall performance.

Note. The size of each segment is not reported by Mode Sense command page 08h, bytes 14 and 15. The value 0XFFFF is always reported regardless of the actual size of the segment. Sending a size specification using the Mode Select command (bytes 14 and 15) does not set up a new segment size. If the STRICT bit in Mode page 00h (byte 2, bit 1) is set to one, the drive responds as it does for any attempt to change an unchangeable parameter.

4.5.1Caching write data

Write caching is a write operation by the drive that makes use of a drive buffer storage area where the data to be written to the medium is stored while the drive performs the Write command.

If read caching is enabled (RCD=0), then data written to the medium is retained in the cache to be made avail- able for future read cache hits. The same buffer space and segmentation is used as set up for read functions. The buffer segmentation scheme is set up or changed independently, having nothing to do with the state of RCD. When a write command is issued, if RCD=0, the cache is first checked to see if any logical blocks that are to be written are already stored in the cache from a previous read or write command. If there are, the respective cache segments are cleared. The new data is cached for subsequent Read commands.

If the number of write data logical blocks exceed the size of the segment being written into, when the end of the segment is reached, the data is written into the beginning of the same cache segment, overwriting the data that was written there at the beginning of the operation; however, the drive does not overwrite data that has not yet been written to the medium.

If write caching is enabled (WCE=1), then the drive may return Good status on a write command after the data has been transferred into the cache, but before the data has been written to the medium. If an error occurs while writing the data to the medium, and Good status has already been returned, a deferred error will be gen- erated.

The Synchronize Cache command may be used to force the drive to write all cached write data to the medium. Upon completion of a Synchronize Cache command, all data received from previous write commands will have been written to the medium.

Table 19 shows the mode default settings for the drive.

4.5.2Prefetch operation

If the Prefetch feature is enabled, data in contiguous logical blocks on the disc immediately beyond that which was requested by a Read command are retrieved and stored in the buffer for immediate transfer from the buffer to the host on subsequent Read commands that request those logical blocks (this is true even if cache operation is disabled). Though the prefetch operation uses the buffer as a cache, finding the requested data in the buffer is a prefetch hit, not a cache operation hit.

To enable Prefetch, use Mode Select page 08h, byte 12, bit 5 (Disable Read Ahead - DRA bit). DRA bit = 0 enables prefetch.

The drive does not use the Max Prefetch field (bytes 8 and 9) or the Prefetch Ceiling field (bytes 10 and 11).

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Savvio 10K.2 SAS Product Manual, Rev. D

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Contents Savvio 10K.2 SAS ST9146802SS ST973402SSPage Contents Defect and error management InstallationSeagate Technology support services Interface requirementsList of Figures Savvio 10K.2 SAS disc drivePage Scope Savvio 10K.2 SAS disc driveSavvio 10K.2 SAS Product Manual, Rev. D Applicable standards and reference documentation StandardsElectromagnetic compatibility Electromagnetic susceptibilityElectromagnetic compliance Electromagnetic compliance for the European UnionAustralian C-Tick Korean MICReference documents European Union Restriction of Hazardous Substances RoHSSavvio 10K.2 SAS Product Manual, Rev. D General description Performance Standard featuresMedia description Factory-installed accessories ReliabilityFormatted capacities Programmable drive capacityFactory-installed options Performance characteristics Internal drive characteristicsSeek performance characteristics Access timeFormat command execution time for 512-byte sectors minutes General performance characteristicsCache operation Start/stop timePrefetch/multi-segmented cache control Caching write data Prefetch operationPage Savvio 10K.2 SAS Product Manual, Rev. D 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 monitorTemperature Log Page 0Dh Parameter Code Description Drive Self Test DSTDST failure definition ImplementationState of the drive prior to testing Invoking DSTShort and extended tests Short test Function Code 001bProduct warranty Log page entriesAbort ShippingProduct repair and return information Physical/electrical specifications AC power requirementsDC power requirements ST9146802SS DC power requirementsST973402SS Gbit mode Amps ST973402SS DC power requirementsGeneral DC power requirement notes Current profiles Power sequencingConducted noise immunity ST973402SS current profile ST973402SS in 3 Gbit operation Power dissipationST9146802SS in 3 Gbit operation Temperature Environmental limitsRelative humidity Effective altitude sea levelShock and vibration ShockPackage size Packaged/product weight Drop height Recommended mountingCorrosive environment Air cleanlinessVibration Acoustics Mechanical specifications Mounting configuration dimensionsSavvio 10K.2 SAS Product Manual, Rev. D Drive error recovery procedures Defect and error managementDrive internal defects/errors Page SAS system errors Background Media ScanIdle Read After Write Media Pre-ScanDeferred Auto-Reallocation Installation Drive orientationCooling Air flowDrive mounting GroundingSavvio 10K.2 SAS Product Manual, Rev. D SAS features Interface requirementsDual port support Command name Command code Supported Scsi commands supportedCommands supported by Savvio SAS family drive Commands supported by Savvio SAS family drive Commands supported by Savvio SAS family drive Commands supported by Savvio SAS family drive Mode Sense data Inquiry dataSavvio inquiry data Bytes Data hexPage Mode Data Header 08 8b b9 98 00 00 02 Miscellaneous operating features and conditions Miscellaneous featuresSupported Feature or condition Miscellaneous statusSAS physical interface Datum B Section C C Section a a Physical characteristics Connector requirementsElectrical description Pin descriptionsSignal characteristics PowerSAS transmitters and receivers Ready LED OutLED drive signal Differential signalsGeneral interface characteristics Eye masks Eye masks overviewReceive eye mask Jitter tolerance masksPeak-to SinusoidalJitter Frequency in kHzTransmitter signal characteristics Signal characteristica Units GbpsReceiver signal characteristics Signal characteristic Units GbpsMaximum allowable jitter Gbps m, n Deterministic jitterqImpedance specifications Receiver jitter toleranceCompliant jitter test pattern Cjtpat Impedance requirements Sheet 1Electrical TxRx connections Transmitter characteristicsImpedance requirements Sheet 2 = -5,437dB Tctf Receiver characteristics ISI loss example at 1.5 GbpsSeagate Technology support services InternetPresales Support Technical SupportData Recovery Services Call Center Toll-free Direct dial Warranty ServiceData Recovery Services Authorized Service Centers Index NumericsPage SAS See also cooling Page Seagate Technology LLC
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ST973402SS, ST9146802SS specifications

The Seagate ST973402SS and ST9146802SS are high-performance, enterprise-grade hard drives designed to meet the demanding needs of data-intensive applications. These drives are part of Seagate's Savvio and Barracuda product lines, aimed specifically at businesses and institutions requiring reliability, speed, and efficiency in storage solutions.

The ST973402SS is a 73GB, 2.5-inch hard drive, while the ST9146802SS offers a larger capacity of 146GB. Both models utilize a 10,000 RPM spindle speed, which significantly enhances their ability to handle fast data read and write operations. This speed ensures reduced latency and improved overall performance, making them ideal for environments where rapid access to data is crucial.

One of the standout features of these drives is their support for Serial Attached SCSI (SAS) interface. SAS technology provides a point-to-point connection, which allows for increased data transfer rates compared to traditional SATA drives. The ST973402SS and ST9146802SS are capable of transferring data at speeds of up to 600 MB/s, facilitating efficient data transfers in enterprise systems.

In terms of reliability, both models offer advanced features designed to improve data integrity and durability. They are built to withstand high workloads, with an annualized workload rate of up to 550 TB per year. This makes them well-suited for applications like databases and transactional storage, where sustained performance is required. Additionally, the drives feature Seagate’s PowerFit technology, which optimizes performance while minimizing power consumption.

To enhance data security, the drives come equipped with self-encrypting technology, ensuring that sensitive data is protected through hardware-based encryption. This is particularly important in environments where data breaches can lead to significant operational impacts.

The drives are also designed to operate efficiently in terms of thermal management, featuring robust heat dissipation capabilities. This helps to maintain optimal performance levels while prolonging the lifespan of the drives.

Overall, the Seagate ST973402SS and ST9146802SS are robust and reliable hard drives that cater to the needs of enterprise environments, combining high capacity, exceptional speed, advanced security features, and energy efficiency to help businesses maintain and manage large volumes of data effectively. With their proven performance and innovative technologies, these drives are well-equipped to support a wide range of applications in modern data centers.