Quantum DLT 1 Interface Manual page 66

Chapter 4: SCSI Commands
Table 4-14. LOG SENSE (4Dh) Command Descriptor Block — Field Descriptions (Continued)
Field Name
PPC
SP
PC
4-24
Description
Parameter Pointer Control. This bit must be 0. A Parameter Pointer Control bit of 0
indicates that the parameter data requested from the tape drive starts with the
parameter code specified in the Parameter Pointer field. It also returns the number
of bytes specified in the Allocation Length field in ascending order of parameter
codes from the specified log page. A PPC bit of 0 and a Parameter Point field of 0
cause all available parameter data for that page code to be returned to the initiator.
Note: The current implementation of the Read/Write Compression Page does not
support a parameter pointer other than 0.
If the PPC bit is set or the Parameter Pointer is larger than the highest numbered
parameter on the page, the target terminates the command with CHECK
CONDITION status. It sets the Sense Key to ILLEGAL REQUEST and the
Additional Sense Code to INVALID FIELD IN CDB.
If the target does not support a parameter code within this page, it does not return
any data associated with this parameter.
Saving Log Parameters. Not supported, this bit is always 0.
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.
Page Control. This field defines the type of parameter values to be returned:
PC
00b
01b
10b
11b
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
tape drive (either by power cycling, BUS DEVICE RESET, or SCSI BUS
RESET).
The Default Cumulative Values are the values to which each parameter is
initialized on a reset condition, as described previously.
By default, current Threshold Values = Default Threshold Values.
Note: All types of parameter values are changeable through LOG SELECT.
July 2004
Type of Parameter Values
Threshold Values
Cumulative Values
Default Threshold Values
Default Cumulative Values
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