M2488 PRODUCT GUIDE TAPE UNIT SCSI COMMANDS
April 1997 CG00000-011503 REV. A 4-115
4-3.26 REWIND command 01h
The REWIND command causes the logical unit to position to the beginning of tape. Any buffered
write data and filemarks are written to the tape before the positioning is performed.
A single REWIND command may not actually cause the tape head to be physically positioned at the
beginning of the tape; positioning may occur only in the buffer or the tape head may be physically
positioned just before the first block but after the Density ID mark on the tape. Issuing two consecu-
tive REWIND commands forces the logical unit to position the tape head a t the physical beginning of
tape. (This may prove useful for test purposes; e.g. The Density ID mark will always be read for a
Read command following two consecutive REWIND commands.
4-3.26.1 REWIND CDB Description
REWIND is a six-byte command. The bytes are as shown below and described in Table 4-106.
Common fields are described in paragraph 4-3.1 on page 4-4.
4-3.26.2 REWIND CHECK CONDITION St atus
If the status reported for the previous command was a CHECK CONDITION because data could
not be written to the tape, then any buffered data is discarded before the rewind occurs.
If CHECK CONDITION status is reported for a REWIND command with the Immediate bit set to
1, then the rewind will not occur.
BITS
BYTES 7 6 5 4 3 2 1 0
000000001
1LUN Reserved Immed
2Reserved
3Reserved
4Reserved
5Reserved Flag Link
Note: Changeable fields in the CDB are shaded.
Table 4-106. REWIND Field Description
BYTE BIT VALUE DESCRIPTION
0 0-7 01h Operation code for the rewind command.
1 0 0
1
If the Immed (Immediate) bit is 0, Status is not returned for the REWIND
command until the rewind has completed or has failed.
If the Immed (Immediate) bit is 1, Status is returned for the REWIND
command as soon as the CDB has been validated and any buffered write
data and filemarks have been written to tape. The rewind operation has
been started but not necessarily completed when status is returned.