User Manual

SCSI Commands Reference Manual, Rev. J 328
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5.2.9 Error counter log pages (WRITE, READ, and VERIFY)
This subclause defines the error counter log pages (see table 299).
Table 300 defines the parameter codes for the error counter log pages.
Table 299 Error counter log page codes
Page Code Loge Page Name
03h / 00h
Read Error Counter
05h / 00h
Verify Error Counter
02h / 00h
Write Error Counter
Table 300 Parameter codes for error counter log pages
Parameter
code
Description
Resettable or
Changeable
[a]
0000h
Errors corrected without substantial delay. An error correction was applied to get perfect data (a.k.a., ECC
on-the-fly). “Without Substantial Delay” means the correction did not postpone reading of later sectors
(e.g., a revolution was not lost). The counter is incremented once for each logical block that requires cor-
rection. Two different blocks corrected during the same command are counted as two events.
Reset Only
0001h
Errors corrected with possible delays. An error code or algorithm (e.g.,ECC, checksum) is applied in order
to get perfect data with substantial delay. “With possible delay” means the correction took longer than a
sector time so that reading/writing of subsequent sectors was delayed (e.g, a lost revolution). The
counter is incremented once for each logical block that requires correction. A block with a double error
that is correctable counts as one event and two different blocks corrected during the same command
count as two events.
Reset Only
0002h
Total (e.g., rewrites or rereads). This parameter code specifies the counter counting the number of errors
that are corrected by applying retries. This counts errors recovered, not the number of retries. If five
retries were required to recover one block of data, the counter increments by one, not five. The counter
is incremented once for each logical block that is recovered using retries. If an error is not recoverable
while applying retries and is recovered by ECC, it isn’t counted by this counter; it will be counted by the
counter specified by parameter code 01h–Error Corrected With Possible Delay.
Reset Only
0003h
Total errors corrected. This counter counts the total of parameter code errors 00h, 01h, and 02h. There is
to be no “double counting
”
of data errors among these three counters. The sum of all correctable errors
can be reached by adding parameter code 01h and 02h errors, not by using this total.
Reset Only
0004h
Total times correction algorithm processed. This parameter code specifies the counter that counts the
total number of retries, or “times the retry algorithm is invoked.” If after five attempts a counter 02h type
error is recovered, then five is added to this counter. If three retries are required to get a stable ECC syn-
drome before a counter 01h type error is corrected, then those three retries are also counted here. The
number of retries applied to unsuccessfully recover an error (counter 06h type error) are also counted by
this counter.
Reset Only
0005h
Total bytes processed. This parameter code specifies the counter that counts the total number of bytes
either successfully or unsuccessfully read, written, or verified (depending on the log page) from the
drive. If a transfer terminates early because of an unrecoverable error, only the logical blocks up to and
including the one with the unrecoverable error are counted.
Reset Only
0006h
Total uncorrected errors. This parameter code specifies the counter that contains the total number of
blocks for which an uncorrected data error has occurred.
Reset Only
0007h - 7FFFh
Reserved
Reset Only
8000h - FFFFh
Vendor specific
Reset Only
[a] The keywords in this column -- Always, Reset Only, and Never -- are defined in 5.2.2.3.