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 14: Read and write retry count maximum recovery times

 

Maximum recovery time per

Read retry count

LBA (cumulative, msec)

 

 

 

 

0

67.43

 

 

1

77.81

 

 

2

264.54

 

 

3

300.85

 

 

4

344.60

 

 

5

378.72

 

 

6

420.21

 

 

7

529.22

 

 

8

617.62

 

 

9

659.11

 

 

10

705.80

 

 

11 (default)

1693.67

 

 

Write retry count

Maximum recovery time per

LBA (cumulative, msec)

 

 

 

 

0

31.12

 

 

1

46.68

 

 

2

72.62

 

 

3

88.18

 

 

4

155.73

 

 

5 (default)

192.04

 

 

Setting these retry counts to a value below the default setting could result in degradation of the unrecovered error rate. For example, suppose the read/write recovery page has the RC bit = 0, the read retry count set to 4, and the recovery time limit set to 450. A 4-block read command can take up to 371 msec recovery time for each block and a maximum of 450 msec recovery for all four blocks. If either of these limits is reached and a block has not yet been recovered, the command will end with Check Condition status and an unrecoverable read error will be reported.

7.3SAS system errors

Information on the reporting of operational errors or faults across the interface is given in the SAS Interface Manual. The SSP Response returns information to the host about numerous kinds of errors or faults. The Receive Diagnostic Results reports the results of diagnostic operations performed by the drive.

Status returned by the drive to the initiator is described in the SAS Interface Manual. Status reporting plays a role in systems error management and its use in that respect is described in sections where the various com- mands are discussed.

7.4Background Media Scan

Background Media Scan (BMS) is a self-initiated media scan. BMS is defined in the T10 document SPC-4 available from the T10 committee. BMS performs sequential reads across the entire pack of the media while the drive is idle. In RAID arrays, BMS allows hot spare drives to be scanned for defects prior to being put into service by the host system. On regular duty drives, if the host system makes use of the BMS Log Page, it can avoid placing data in suspect locations on the media. Unreadable and recovered error sites will be logged or reallocated per ARRE/AWRE settings.

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.

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

39

Page 48 Page 50
Page 49
Image 49
Seagate ST9146802SS, ST973402SS manual SAS system errors, Background Media Scan
Page 48 Page 50

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.
Top Page Image Contents