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 21 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).

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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Cheetah 15K.6 FC Product Manual, Rev. C

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Seagate ST3450056FC (FDE), ST3146756FC (FDE), ST3300056FC (FDE) manual Prefetch operation
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ST3450056FC (FDE), ST3146756FC (FDE), ST3300056FC (FDE) specifications

Seagate has established itself as a leader in data storage solutions, and among its high-performance offerings are the Seagate ST3300056FC (FDE), ST3146756FC (FDE), and ST3450056FC (FDE) drives. These drives are part of Seagate's enterprise-class, 3.5-inch form factor family, providing robust data security, reliability, and performance for demanding data center environments.

The ST3300056FC boasts a capacity of 3TB, making it ideal for applications that require substantial storage space. With a 7200 RPM spindle speed and a 6Gb/s Serial Attached SCSI (SAS) interface, this drive delivers rapid data access speeds and high throughput, catering to the needs of enterprise workflows and data-intensive applications. The FDE (Full Disk Encryption) feature ensures that all stored data is encrypted, providing an added layer of protection against unauthorized access, which is critical for businesses handling sensitive information.

Similarly, the ST3146756FC offers a 1.4TB capacity, also spinning at 7200 RPM and utilizing a 6Gb/s SAS interface. As with its counterpart, this drive incorporates FDE technology, making it an excellent choice for environments that prioritize data security while maintaining performance. The SAS interface enhances connectivity options and further improves reliability and data integrity, essential for mission-critical applications.

The ST3450056FC, with a capacity of 4.5TB, stands out as a powerful option for storage needs that exceed traditional offerings. With the same 7200 RPM spindle speed and 6Gb/s SAS interface, it ensures optimal performance across various workloads. The FDE functionality further enhances its appeal, making it suitable for organizations that must comply with stringent data protection regulations.

All three drives are built with Seagate's advanced technologies, including PowerBalance, which maximizes the spindle performance while optimizing power consumption and thermal management. They are also designed with vibration tolerance, enhancing their reliability in multi-drive systems and environments where space and airflow may be limited.

In summary, the Seagate ST3300056FC, ST3146756FC, and ST3450056FC drives exemplify cutting-edge engineering, catering to enterprise needs with their impressive capacities, robust performance, and built-in security. They are well-suited for organizations that prioritize reliability and data integrity, making them a vital component of modern storage infrastructures.
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