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6.10
BYTE
01
02
03
04
05
Valid Errors:
Error
Drive Not Ready
Bad Argument
Cartridge Changed
Initiator Detected Error
SCSI Bus Out Parity Error
Adapter Parity Check
READ/RESET USAGE COUNTER
BIT
Error Code
07
06
05
04
03
02
01
00
------1------1------1------1------1------1------1------
0 0 0 1 0 0 0
0
Logical Unit Number
1
Reserved (0)
Reserved (0)
Reserved (0)
Bytes Allocated
(09 )
Reserved (0)
I
Flag
1
Link
Figure
6-l7~
READ/RESET USAGE COUNTER Command
The READ/RESET USAGE COUNTERS command recovers the
information
stored by the ACB-5500 for
the particular disk device.
The
information is valuable to observe the statistical performance of
the device and to point to devices which may need service before
their performance degrades system operation.
Ail seeks and sectors read are counted in three byte counters.
Seek errors, correctable data errors, and uncorrectable data
errors are counted in one byte counters.
.
When one of
the error
counters
exceeds
the
threshold,
all
subsequent commands for
that device will terminate immediately
with Check Condition status and an error code of 2CH'
Error
Counter Overflow.
This will continue until execution of the
READ/RESET USAGE COUNTER command, which recovers the 9 bytes of
counter information and resets the counters.
500504-00
6-26
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