Page
36
LTO SCSI Interface Manual
LOCATE
The Locate command moves to a specified position on the tape.
Before the locate operation is performed, all buffered data and filemarks are
transferred to tape. On completion, the logical position is before the specified
location.
Command Descriptor Block
Byte
Bits
7
6
5
4
3
2
1
0
0
Operation Code (2Bh)
1
Ignored LUN Reserved
Immed
2
Reserved
3
Block Address, MSB
4
Block Address
5
Block Address
6
Block Address, LSB
7
Reserved
8
Reserved
9
Control
Field Descriptions
Field
Bytes
Bits
Description
Operation
Code
0
The operation code for Locate is 2Bh
Ignored
Logical
Unit
1
5-7
The LUN field is residual from the SCSI-1 days and is ignored.
Immed
1
0
0 = Status is not returned until the tape is positioned.
1 = Status is returned as soon as the operation is initiated.
Block Ad-
dress
3-6
The logical block address of the block to which the tape is to be po-
sitioned. Block 0 is the first block on tape. The value indicates the
total number of records and marks between BOT and the desired
logical position.
Reserved
All reserved bits must be 0.
Control
5
See Control Byte Format on page 18.
The Locate command causes the logical position on tape to be set to the value
indicated by the Block Address field. The value indicates the total number of records
and marks between BOT and the desired logical position. A value of 0 will cause the
tape to be positioned at BOT.
If the Immediate (Immed) flag is set to 1, then the drive validates the command and
waits for any previous command from any host to complete including any immediate
commands currently being processed and for any buffered data to be flushed to
tape. It will then report a deferred error for any preceding command or buffered data
if appropriate. If there is no deferred error, the drive reports good status and initiates
the command. If the Immediate (Immed) flag is set to 0, status is not returned until
after the command has completed.
