REQUEST SENSE 03h
C
omm
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147
REQUEST SENSE
03h
The
REQUEST SENSE
command transfers sense data held within the drive to the host during a data-
in phase. The data is valid in the following circumstances:
•
After reporting
CHECK CONDITION
status to the host.
•
After a command has terminated with an unexpected
BUS FREE
.
•
Immediately after the following commands that cause tape motion:
Positional sense data is valid whenever media is present and loaded and no higher priority sense
data is present. An unsolicited request sense (that is, one with no preceding
CHECK CONDITION
)
will result in sense data with no valid data, which will be all zeros.
NOTE:
The drive maintains valid positional information for normal read and write commands
only (
READ
,
WRITE
,
SPACE
,
WRITE FILEMARKS
,
REWIND
). If abnormal commands (such as
WRITE
BUFFER
) are received this positional sense information is lost. See “Sense data management”
on page 154.
The drive clears sense data for the host following execution of the
REQUEST SENSE
command for
that host, unless the data is positional sense data.
Pre-execution checks:
Only Illegal Field Check is performed before execution of the command.
Command descriptor block:
CDB fields:
READ
SPACE
VERIFY
WRITE
WRITE FILEMARKS
REWIND
7
6
5
4
3
2
1
0
0
Operation Code (03h)
1
LUN
Reserved (0)
DESC
2–3
Reserved (0)
4
Allocation Length
5
Control
LUN
This field is ignored.
DESC
0 Fixed Format sense data will be returned.
1 Descriptor Format sense data will be returned.
