Reference Guide

Chapter 4 SCSI Commands
LOG SENSE Command (4Dh)
DLT-S4 Interface Reference Guide 72
DS Disable Save. Always set to 1.
TSD Target Save Disable. Always set to 1.
ETC Enable Threshold Comparison. When set to 1, indicates that the drive performs
comparison to threshold. When set to 0, indicates that the drive does not perform
the comparison. The Control Mode Page of the
MODE SELECT command sets this
bit set to 1. Default is 0.
TMC Threshold Met Criteria. This field is valid only if the host sets the ETC bit to 1. This
field determines the basis for comparison. The host specifies this field using the
LOG SELECT command. If the result of comparison is true (cumulative =
threshold) and the
MODE SELECT / SENSE Control Mode Page RLEC bit is set to 1,
the drive generates a
UNIT ATTENTION for all initiators. In that case, the drive sets
the Sense Key to
UNIT ATTENTION, the Additional Sense Code to LOG EXCEPTION,
and the Additional Sense Code Qualifier to
THRESHOLD CONDITION MET. If the
RLEC bit in Control Mode Page is 0, the drive does not generate a
UNIT
ATTENTION
.
Note that comparison is performed in real time. A
LOG SENSE command need not
be issued to get the
CHECK CONDITION status. Once ETC is selected and the RLEC
bit in Control Mode Page is set to 1, the drive issues a
CHECK CONDITION status
based on the criteria defined in the TMC bits if the criteria is met in real time. The
CHECK CONDITION status does not identify for which parameter code the criterion
is met. The host must issue a
LOG SENSE command to read the counters to
determine for which parameter code the criterion has been met.
The criteria for comparison are:
Code Description
00b Every update of the cumulative value
01b Cumulative value equal to the threshold value
10b Cumulative value not equal to the threshold value
11b Cumulative value greater than the threshold value
LBIN List Binary. Always set to 0.
LP List Parameter. Always set to 0.
Parameter Length Specifies the number of bytes in the parameter value. All parameters are 4 bytes in
length except parameter 0005h, which is 8 bytes in length.
Parameter Value Indicates the actual value of this log parameter.
Field Description