Hitachi ULTRASTAR 15K450 HUS154530VLF400 - Manual (Page 176)

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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19.7.13 Log Sense Page 30
This page contains Performance Counters.
Table 136: Log Sense Page 30
Page 30h returns performance counter information. This includes seek counters and buffer overrun/under run counters.
The appropriate seek counter is incremented once during execution of Pre-Fetch, Read, Verify, Write, Write and Verify, Write
Same, and Seek commands.
Buffer Overrun conditions are detected during Read commands.
Buffer Underrun conditions are detected during Verify with ByteChk=1, Write, Write and Verify, and Write Same commands.
Only one seek counter is incremented for each of these commands and the counter is incremented only once per command.
The length of the initial seek that is required to access the first Logical Block specified for the SCSI command determines
which seek counter is incremented. The Zero Seek counter is incremented if a seek is not required or if only a head switch is
Byte
Bit
7 6 5 4 3 2 1 0
0 Reserved Page code = 30h
1 Reserved
2-3 Page Length = 0030h
4-5 Parameter Code = 0000h
6 DU = 0 DS = 0 TSD = 0 ETC = 0 TMC = 0 F&L = 00b
7 Parameter Length = 2Ch
8-9 Zero Seeks
10-11 Seeks > = to 2/3
12-13 Seeks > = 1/3 and < 2/3
14-15 Seeks > = 1/6 and < 1/3
16-17 Seeks > = 1/12 and < 1/6
18-19 Seeks > 0 and < 1/12
20-23 Reserved = 0
24-25 Overrun Counter
26-27 Under run Counter
28-31 Device Cache Full Read Hits
32-35 Device Cache Partial Read Hits
36-39 Device Cache Write Hits
40-43 Device Cache Fast Writes
44-47 Device Cache Read Misses
48-51 Reserved = 0