Quantum DLT 4000 Product Manual page 192

DLT4000 SCSI Interface
Parameter Control Bytes
Byte 2 of Log parameter block in Figure 8-15 is referred to as the parameter control
byte.
DU–Disable Update: DU bit is not defined for LOG SELECT and the target
ignores any value.
DS and TSD–Saving parameters is not supported; they both should be set to 1. If
the DS and/or TSD are set to zero, the command is terminated with CHECK
CONDITION status with the sense key set to ILLEGAL REQUEST with the
additional sense code set to INVALID FIELD IN PARAMETER LIST.
ETC–Enable Threshold Comparison: When set to 1, the drive will perform a
comparison with threshold values once the cumulative value is updated.
Comparison criteria is defined in TMC. If the comparison is met and the RLEC
bit of MODE SELECT/SENSE Control Page is set to 1, then a UNIT
ATTENTION is generated for all initiators. The additional sense code is set to
LOG EXCEPTION and the additional sense code qualifier is set to THRESHOLD
CONDITION MET. If the RLEC bit is zero and the comparison is met, then
UNIT ATTENTION is not generated.
TMC–Threshold Met Criteria: See Figure 8-23 for the list of criteria. Once the
specified criteria in this field is met and the ETC bit is 1 and the RLEC bit in
MODE SENSE/SELECT Control Page is set to 1, then UNIT ATTENTION is
generated for all initiators.
LP–List Parameter: This bit should always be set to 0 to indicate parameter codes
are treated as data counters.
Parameter Length
This field specifies the number of bytes of the parameter value.
8-32 DLT4000/DLT4500/DLT4700 Cartridge Tape Subsystem