Chapter 4: SCSI Commands
4-30
July 2004
81-81276-01 Rev A01
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 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.
This 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 the Control Mode Page is 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 the parameter code for which the
criteria is met. To make this determination, the host
must issue a LOG SENSE command to read the
counters.
Code
00b
01b
10b
11b
Basis of Comparison
Every update of the cumulative value
Cumulative value equal to threshold value
Cumulative value not equal to threshold value
Cumulative value greater than threshold value
LP
List Parameter. This bit is always 0, since the tape drive
treats the parameter codes as data counter. When the
data counter reaches its defined maximum value, it
does not increment and the DU bit is 1. If the data
counter is at or reaches its maximum value during the
execution of a command, the tape drive completes the
command. If the RLEC bit of the Control Mode page
is 1, the tape drive then issues the status of CHECK
CONDITION and sets the Sense Key to RECOVERED
ERROR with Additional Sense Code set to LOG
COUNTER AT MAXIMUM.
Parameter Length
This field specifies the number of bytes of the parameter value.
Parameter Value
This field is the actual value of this log parameter.
Table 4-16.
Read / Write Error LOG SENSE Parameters (Pages 02h and 03h) — Field
Descriptions
(Continued)
Field Name
Description
Summary of Contents for DLTtape DLT1
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