Seagate ST9900805SS Savvio 10K.1 FC Product Manual - Page 46

FC-AL system errors

Get Seagate ST9900805SS PDF manuals and user guides View all Seagate ST9900805SS manuals
Add to My Manuals
Save this manual to your list of manuals

Page 46 highlights

Table 4 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 recovery 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 4: Read and write retry count maximum recovery times Maximum recovery time per Read retry count1 LBA (cumulative, msec) Maximum recovery time per Write retry count1 LBA (cumulative, msec) 0 77.7 0 35.9 1 89.7 1 53.8 2 305 2 83.7 3 353 3 101.7 4 401 4 179.4 5 419 5 (default) 221.3 6 466 7 586 8 676 9 724 10 777 11 (default) 1,591 [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 401 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 FC-AL system errors Information on the reporting of operational errors or faults across the interface is given in the Fibre Channel Interface Manual. The FCP 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 Fibre Channel 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 FC Product Manual, Rev. D

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
40
Savvio FC Product Manual, Rev. D
Table 4 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.
[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 401 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
FC-AL system errors
Information on the reporting of operational errors or faults across the interface is given in the
Fibre Channel
Interface Manual
. The FCP 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
Fibre Channel 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.
Table 4:
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
77.7
0
35.9
1
89.7
1
53.8
2
305
2
83.7
3
353
3
101.7
4
401
4
179.4
5
419
5 (default)
221.3
6
466
7
586
8
676
9
724
10
777
11 (default)
1,591