4-3.22 Release Unit Command 17H; 4-3.22.1 Release Unit Cdb Description; Table 4-98. Release Unit Field Description - Fujitsu M2488 Product Manual

M2488 PRODUCT GUIDE
4-3.22 RELEASE UNIT command 17h
The RESERVE UNIT and RELEASE UNIT commands serve to resolve contention in multiple-initi-
ator systems. The RELEASE UNIT command is used to release previously reserved logical units for
the requesting initiator, or if it is a third-party release, for another specified SCSI device.
The SCSI device that releases the reservation of the tape logical unit, also automatically releases the
reservation of the medium changer logical unit, even though the RELEASE UNIT command was
directed to the tape logical unit. This is because the SCSI device that gains the reservation of the tape
logical unit also automatically gains the reservation of the medium changer logical unit.
The RESERVE UNIT and RELEASE UNIT commands are not supported for the medium changer
logical unit, however, releasing the reservation of the tape logical unit will serve as a method of
releasing the medium changer logical unit as well.
4-3.22.1 RELEASE UNIT CDB Description
RELEASE UNIT is a six-byte command. The bytes are shown below and described in Table 4-98.
Common fields are described in paragraph 4-3.1 on page 4-4
BYTES 7
0 0
1
2
3
4
5
Note: Changeable fields in the CDB are shaded.
BYTE BIT VALUE
0 0-7
1 1-3
1 4
April 1997
6 5 4
0 0 1
LUN 3rd Party
Reserved

Table 4-98. RELEASE UNIT Field Description

17h Operation Code.
The 3rd Party Dev ID is the SCSI device for whom a third-party reserva-
tion has been made.
0 If the 3rd Party bit is zero, then the initiator that made the non-third-party
reservation, releases the reserved device.
1 If the 3rd Party bit is one, the initiator that made a third-party reservation
for the device specified in the "3rd Party Dev ID" field releases the reser-
vation for that same device.
CG00000-011503 REV. A
TAPE UNIT SCSI COMMANDS
.
BITS
3 2
0 1
3rd Party Dev ID
Reserved
Reserved
Reserved
DESCRIPTION
1 0
1 1
Reserved
Flag Link
4-101