User's Guide

Chapter 3 Emulated DLT7000 SCSI Commands
Log Sense (4Dh)
Quantum DX-Series Software Interface Guide 161
Error Detection
Summary in LOG
SENSE Command
Descriptor Block
3
The following conditions constitute errors detected by the drive relating
to the LOG SENSE command descriptor block. The request sense data is
set to ILLEGAL REQUEST, INVALID FIELD IN CDB.
Error conditions occur when:
• A page is not supported
• The parameter pointer is larger than the highest numbered parameter
on the page
• The SP bit is set to 1
• The Allocation Length is smaller than the data being returned by the
target.
• PPC bit set to 1
Parameter Pointer The Parameter Pointer field allows the host to specify at which parameter
within a log page the requested data should begin. For example, if a page
supports parameters 0 through 5, and the Parameter Pointer contains 3,
then only parameters 3, 4, and 5 are returned to the initiator. Similarly, if a
page supports parameters 1, 3, and 6, and the Parameter Pointer contains
2, then only parameters 3 and 6 are returned to the initiator.
If the Parameter Pointer is larger than the highest numbered parameter on
the page, 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.
Note that parameters within a page are always returned in ascending
order according to parameter code.
If the target does not support a parameter code within this page then it
does not return any data associated with this parameter.
Allocation Length
The Allocation Length field is used to inform the target how much space
the initiator has allocated for data. The host uses this field to limit the size
of data transfers to its own internal buffer size.
Field Name Description