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Western Digital Hard Disk Drive OEM Specification
11.23.7
Read Stream Error log
Table 166 defines the format of the Read Stream Error log. Entries are placed into the Read Stream Error log only
when the SE bit is set to one in the Status Register. The 512 bytes returned shall contain a maximum of 31 error
entries. The Read Stream Error Count shall contain the total number of Read Stream Errors detected since the last
successful completion of the Read Log Ext command with LBA Low register set to 22h. This error count may be
greater than 31, but only the most recent 31 errors are represented by entries in the log. If the Read Stream Error
Count reaches the maximum value that can be represented after the next error is detected the Read Stream Error
Count shall remain at the maximum value. After successful completion of a Read Log Ext command with the LBA
Low Register set to 22h, the Read Stream Error Log shall be reset to a power-on or hardware reset condition, with
the Error Log Index and Read Stream Error Count cleared to zero. The Read Stream Error Log is not preserved
across power cycles and hardware reset.
Description
Bytes
Offset
Structure Version
1
00h
Error Log Index
1
01h
Read Stream Error Log Count
2
02h
Reserved
12
04h
Read Stream Error Log Entry #1
16
10h
Read Stream Error Log Entry #2
16
20h
...
Read Stream Error Log Entry #31
16
1F0h
512
Table 166 Read Stream Error Log
The Data Structure Version field shall contain a value of 02h indicating the second revision of the structure format.
The Read Stream Error Log Count field shall contain the number of uncorrected sector entries currently reportable to
the host. This value may exceed 31.
The Error Log Index indicates the error log data structure representing the most recent error. Only values (31:1) are
valid.
Table 166 defines the format of each entry in the Read Stream Error Log.
Description
Bytes
Offset
Feature Register Contents Value (current)
1
00h
Feature Register Contents Value (previous)
1
01h
Status Register Contents Value
1
02h
Error Register Contents Value
1
03h
LBA (7:0)
1
04h
LBA (15:8)
1
05h
LBA (23:16)
1
06h
LBA (31:24)
1
07h
LBA (39:32)
1
08h
LBA (47:40)
1
09h
Reserved
2
0A-0Bh
Sector Count (LSB)
1
0Ch
Sector Count (MSB)
1
0Dh
Reserved
2
0E-0Fh
Table 167 Stream Error Log entry
Byte (1:0) contains the contents of the Feature Register when the error occurred. This Value shall be set to
0FFFFh for s deferred write error.
Byte 2 contains the contents of the Status Register when the error occurred.