Seagate ST300MM0026 Savvio 10K.1 SAS Product Manual - Page 46

SAS system errors

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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 count1 LBA (cumulative, msec) 0 51.97 1 59.97 2 203.9 3 219.9 4 243.9 5 275.9 6 347.8 7 355.8 8 371.8 9 407.8 10 444.4 11 (default) 980.1 Maximum recovery time per Write retry count1 LBA (cumulative, msec) 0 24.0 1 36.0 2 40.0 3 76.0 4 151.9 5 (default) 179.9 [1] 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 244 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. 7.3 SAS 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 commands are discussed. 40 Savvio SAS Product Manual, Rev. D

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40
Savvio SAS Product Manual, Rev. D
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.
[1]
Setting these retry counts to a value below the default setting could result in degradation of the unrecov-
ered 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 244 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 sta-
tus and an unrecoverable read error will be reported.
7.3
SAS 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.
Table 14:
Read and write retry count maximum recovery times
Read retry count
1
Maximum recovery time per
LBA (cumulative, msec)
Write retry count
1
Maximum recovery time per
LBA (cumulative, msec)
0
51.97
0
24.0
1
59.97
1
36.0
2
203.9
2
40.0
3
219.9
3
76.0
4
243.9
4
151.9
5
275.9
5 (default)
179.9
6
347.8
7
355.8
8
371.8
9
407.8
10
444.4
11 (default)
980.1