108.29

The drive firmware error recovery algorithms consists of 11 levels for read recoveries and five levels for write. Each level may consist of multiple steps, where a step is defined as a recovery function involving a single re- read or re-write attempt. The maximum level used by the drive in LBA recovery is determined by the read and write retry counts.

Table 5 equates the read and write retry count with the maximum possible recovery time for read and write recovery of individual LBAs. The times given do not include time taken to perform reallocations. Reallocations are performed when the ARRE bit (for reads) or AWRE bit (for writes) is one, the RC bit is zero, and the recov- ery time limit for the command has not yet been met. Time needed to perform reallocation is not counted against the recovery time limit.

When the RC bit is one, reallocations are disabled even if the ARRE or AWRE bits are one. The drive will still perform data recovery actions within the limits defined by the Read Retry Count, Write Retry Count, and Recovery Time Limit parameters. However, the drive does not report any unrecovered errors.

Table 5: Read and write retry count maximum recovery times

Read retry count1	Maximum recovery time per
Read retry count1	LBA (cumulative, msec)

0	108.29

1	124.95

2	424.83

3	483.14

4	583.78

5	646.11

6	712.75

7	870.69

8	964.71

9	1031.35

10	1089.66

11 (default)	2369.00

Write retry count1	Maximum recovery time per
Write retry count1	LBA (cumulative, msec)

0	49.98

1	74.97

2	116.62

3	141.61

4	250.08

5 (default)	308.39

[1]These values are subject to change.

Setting these retry counts to a value below the default setting could result in degradation of the unrecov- ered error rate which may exceed the value given in this product manual. A setting of zero (0) will result in the drive not performing error recovery.

For example, suppose the read/write recovery page has the RC bit set to 0, read retry count set to 4, and the recovery time limit field (Mode Sense page 01, bytes 10 and 11) set to FF FF hex (maximum). A four LBA Read command is allowed to take up to 297.38 msec recovery time for each of the four LBAs in the command. If the recovery time limit is set to 00 C8 hex (200 msec decimal) a four LBA read command is allowed to take up to 200 msec for all error recovery within that command. The use of the Recovery Time Limit field allows finer granularity on control of the time spent in error recovery. The recovery time limit only starts counting when the drive is executing error recovery and it restarts on each command. There- fore, each command’s total recovery time is subject to the recovery time limit. Note: A recovery time limit of 0 will use the drive’s default value of FF FF. Minimum recovery time limit is achieved by setting the Recovery Time Limit field to 00 01.

36	Barracuda ES.2 SAS Product Manual, Rev. E

ST31000640SS, ST3500620SS, ST3750630SS specifications

Seagate has been a leading name in the storage industry for decades, and its range of enterprise-class hard drives showcases advanced technologies and robust performance. The Seagate ST3750630SS, ST3500620SS, and ST31000640SS are three notable models that cater to the demands of data centers and enterprises. Each model is designed with specific features that enhance reliability and efficiency, making them suitable for various applications.

The Seagate ST3750630SS is a 750GB 15K RPM Serial Attached SCSI (SAS) drive. It boasts a high-performance architecture that allows for fast data transfer rates, making it ideal for high-load environments such as transaction processing and video streaming. This drive features an MTBF of 1.6 million hours, ensuring minimal downtime due to failures. It also employs advanced error recovery and data protection mechanisms, including error correction codes (ECC), to maintain data integrity.

Meanwhile, the ST3500620SS offers a capacity of 500GB with a spinning speed of 15K RPM as well. This drive utilizes the SAS interface, providing users with improved bandwidth and connectivity compared to traditional SATA drives. The ST3500620SS is designed with a focus on high availability, featuring a robust design that supports multiple workloads simultaneously. Its quick access times enhance overall system performance, making it a preferred choice for high-performance computing applications.

The ST31000640SS is another enterprise-class offering, delivering 1TB of storage capacity. Like its counterparts, this drive operates at 15K RPM and utilizes the SAS interface, facilitating fast data processing and retrieval. It also incorporates a dual-port design which allows for redundancy and failover capabilities. This feature is critical in enterprise environments where data access and uptime are paramount. The drive's design is optimized for durability and longevity, best suited for environments that require 24/7 operation.

All three Seagate drives feature advanced technologies such as dual-stage actuators and thermal write technology, ensuring improved read and write performance, along with reduced power consumption. Additionally, they are built to endure the rigors of enterprise workloads, including heavy I/O operations and high access demands.

In summary, the Seagate ST3750630SS, ST3500620SS, and ST31000640SS are exemplary models that reflect the company’s commitment to quality and performance in enterprise storage solutions. With their high speeds, reliability, and extensive features, these drives are well-equipped to meet the challenges of modern data-driven environments.

Seagate ST3750630SS, ST31000640SS, ST3500620SS manual 108.29

Models: ST31000640SS ST3500620SS ST3750630SS

Barracuda ES.2 SAS Product Manual, Rev. E

ST31000640SS, ST3500620SS, ST3750630SS specifications