128 Commands
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 131.
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:
READ SPACE VERIFY
WRITE WRITE FILEMARKS REWIND
7 6 5 4 3 2 1 0
0
Operation Code (03h)
1
Reserved (0)
3
4
Allocation Length
5
Control
