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5-40 Quantum DLT 7000 Tape System
LOG SENSE Command (4Dh) (continued)
Table 5–19 LOG SENSE Command Descriptor Block - Field Descriptions
Field Name Description
PPC Parameter Pointer Control. This bit must be set to 0. A PPC of 0 indicates that the
parameter data requested from the device starts with the parameter code
specified in the Parameter Pointer field (Bytes 5 - 6) and return the number of
bytes specified in the Allocation Length field (Bytes 7 - 8) in ascending order of
parameter codes from the specified log page.
Note that the current implementation of the READ/WRITE COMPRESSION page
does not support a PPC other than 0.
If PPC bit is set, then the target terminates the command with CHECK CONDITION
status, sense key set to ILLEGAL REQUEST, and additional sense code set to
INVALID FIELD IN CDB.
SP Save Parameters. Not supported, must be set to 0. If for some reason the Save
Parameters bit is set, the command terminates with a CHECK CONDITION status
with a sense key of ILLEGAL REQUEST and an ASC of INVALID FIELD IN CDB.
PC Page Control. This field defines the type of parameter values to be returned:
PC - Type of Parameter Values
00b - Threshold Values
01b - Cumulative Values
10b - Default Threshold Values
11b - Default Cumulative Values
The Default Threshold Values are the maximum values that each parameter can
attain.
The Current Cumulative Values are the values computed since the last reset of the
device (either via power-cycle, BUS DEVICE RESET, or SCSI RESET.
The Default Cumulative Values are the values to which each parameter is
initialized at a reset condition. Default values are zero.
By default, Current Threshold Values = Default Threshold Values.
Note that all types of parameter values are changeable via LOG SELECT.