LOG SENSE (4Dh)
The LOG SENSE command allows the host to retrieve statistical information maintained by the media
changer about its own hardware. The statistical information is divided over several pages. A LOG SENSE
command will retrieve one of these pages.
Bit 7 6 5 4 3 2 1 0
Byte
0 Operation Code (4Dh)
1 LUN Reserved PPC (0) SP (0)
2 PC Page Code
3 Reserved
4 Reserved
5 (MSB) Parameter pointer
6 (LSB)
7 (MSB) Allocation length
8 (LSB)
9 Control
Field descriptions:
PPC: If Parameter Pointer Control bit is set, the target terminates the command with Check Condition
status. The sense key is set to ILLEGAL REQUEST, and an additional sense code of INVALID
FIELD IN CDB.
SP: Saving Log Parameters (SP) is not supported. If the SP bit is set, the command is terminated with
Check Condition status with the sense key set to ILLEGAL REQUEST, and an additional sense
code of INVALID FIELD IN CDB.
PC: The Page Control field defines the type of parameter value to be returned. This field should either
be set to 00b (Current Threshold Values) or 01b (Current Cumulative Values). If not, the command
is terminated with Check Condition status with the sense key set to ILLEGAL REQUEST, and an
additional sense code of INVALID FIELD IN CDB. The Current Cumulative Values are the values
computed since the last reset of the device (either by power-cycling, Bus Device Reset, or SCSI
Reset).
Note: Only Log Sense Tape Alert page (2Eh) supports PC being set to Current Threshold Values.
Page
Code:
The Page Code field identifies which log page is being requested by the initiator. If the page is not
supported then the command terminates with a Check Condition status with the sense key set to
ILLEGAL REQUEST, and an additional sense code of INVALID FIELD IN CDB. Supported pages
are:
v 00h -List of Supported Pages Page
v 07h -Event Log Page
v 2Eh -Tape Alert Page
v 30h -Statistics Counter Page
v 33h -Error Log Page
Parameter
Pointer:
The Parameter Pointer field allows the host to specify at which parameter within a Log Page the
requested data should begin. This is not supported in any Log Sense page and should be set to 0.
Chapter 3. Supported SCSI Commands 3-11
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