Seagate ST32000446SS, ST31000425SS, ST31000424SS manual Caching write data, Prefetch operation

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5.5.1Caching 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 10 shows the mode default settings for the drive.

5.5.2Prefetch 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 buf- fer 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).

When prefetch (read look-ahead) is enabled (enabled by DRA = 0), the drive enables prefetch of contiguous blocks from the disc when it senses that a prefetch hit will likely occur. The drive disables prefetch when it decides that a prefetch hit is not likely to occur.

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Contents ST32000446SS ST31000426SS ST3500416SS Standard Models Self-Encrypting Drive ModelsSED Fips 140-2 Models Revision history Contents Installation Defect and error managementAbout Fips About self-encrypting drives Interface requirementsPower Constellation ES Series SAS Product Manual, Rev. E List of Figures Constellation ES Series SAS Product Manual, Rev. E Seagate Online Support and Services Seagate Technology support servicesScope Standards Applicable standards and reference documentationElectromagnetic compatibility Electromagnetic susceptibilityElectromagnetic compliance for the European Union Electromagnetic complianceAustralian C-Tick Korean KCCEuropean Union Restriction of Hazardous Substances RoHS Reference documentsGeneral description Media description Standard featuresReliability PerformanceFormatted capacities Programmable drive capacityFactory-installed options Internal drive characteristics Performance characteristicsSeek performance characteristics Access timeStart/stop time General performance characteristicsCache operation Prefetch/multi-segmented cache controlPrefetch operation Caching write dataError rates Reliability specificationsRecoverable Errors Unrecoverable ErrorsSeek errors Reliability and serviceInterface errors Preventive maintenanceControlling S.M.A.R.T 4 S.M.A.R.TPerformance impact Reporting controlTemperature Log Page 0Dh Parameter Code Description Predictive failuresThermal monitor Drive Self Test DST State of the drive prior to testingDST failure definition ImplementationShort test Function Code 001b Short and extended testsExtended test Function Code 010b Log page entriesProduct warranty ShippingProduct repair and return information Physical/electrical specifications PowerChoiceTM power managementPowerChoice modes DC power requirements AC power requirementsConstellation ES Series SAS Product Manual, Rev. E Constellation ES Series SAS Product Manual, Rev. E Page General DC power requirement notes Power sequencingConducted noise immunity TB model current profiles Current profilesConstellation ES Series SAS Product Manual, Rev. E 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 ST3500414SS CURRENT/POWER vs Throughput SAS 3.0GB 500GB models in 3Gb operationOs per Second 500GB models in 6Gb operation Temperature a. Operating Environmental limitsRelative humidity Effective altitude sea level a. Operating Shock and vibrationShock Recommended mounting Vibration a. Operating-normal Air cleanlinessAcoustics Corrosive environmentElectromagnetic susceptibility Mounting configuration dimensions Mechanical specificationsAbout Fips PurposeLevel 2 security Admin SP Controlled accessAbout self-encrypting drives Data encryptionRandom number generator RNG Default passwordDrive locking Data bandsPower requirements Authenticated firmware downloadSupported commands Cryptographic eraseDefect and error management Drive internal defects/errorsDrive error recovery procedures SAS system errors Background Media Scan Media Pre-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 Mode Sense data Inquiry 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 operating features and conditions Miscellaneous featuresMiscellaneous status SAS physical interface Datum B Section C C Section a a Connector requirements Physical characteristicsElectrical description Pin descriptionsPower Signal characteristicsSAS transmitters and receivers Ready LED OutLED drive signal SAS-2 Specification ComplianceDifferential signals General interface characteristicsNumerics IndexKCC Msid Mtbf See also cooling Page Constellation ES Series SAS Product Manual, Rev. E Page Seagate Technology LLC

ST3500414SS, ST3500415SS, ST32000445SS, ST31000425SS, ST32000446SS specifications

Seagate, a leader in data storage solutions, has introduced a range of high-capacity and reliable hard drives designed for enterprise environments, including the Seagate ST31000424SS, ST3500416SS, ST31000426SS, ST32000444SS, and ST32000446SS. Each of these models is built with an emphasis on performance, endurance, and advanced data protection technologies, catering to mission-critical applications and data-intensive workloads.

The ST31000424SS is a 1TB drive designed for servers and data centers. It offers a 7,200 RPM spindle speed and a 6 Gb/s SATA interface, ensuring quick data access and transfer rates. With a 64MB cache buffer, the ST31000424SS provides enhanced read/write performance, making it suitable for applications that demand quick responses from the storage subsystem.

Similarly, the ST3500416SS is a high-capacity 500GB model, also spinning at 7,200 RPM with a 6 Gb/s SATA interface. This drive is ideal for mid-range servers and enterprise storage, providing an excellent balance of performance and capacity for users looking to optimize their storage efficiency while maintaining lower power consumption.

The ST31000426SS expands the capacity to 1TB while retaining the same reliability and performance characteristics as its counterparts. Its robust design ensures reliability in multi-drive environments, making it an appealing choice for virtualization and database applications, where performance is critical.

The ST32000444SS and ST32000446SS represent Seagate's commitment to higher capacities, with both offering 2TB of storage. They both feature 7,200 RPM speeds, 6 Gb/s SATA interfaces, and 64MB cache buffers, catering to high-demand environments such as cloud storage and data analytics. The drives also integrate advanced error recovery and data integrity features, ensuring the protection of sensitive data, which is vital for enterprise users.

Each model supports Seagate's PowerChoice technology, which optimizes power consumption without sacrificing performance, enhancing energy efficiency in modern data centers. With a broad range of capacities and performance levels, these Seagate drives provide scalable solutions tailored to meet the robust demands of today’s enterprise applications, ensuring reliability and performance for critical data operations.
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