C141-E039-01EN
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3.1.11
RESERVE (16)
Bit
Byte
7
6
5
4
3
2
1
0
0
X‘16’
1
LUN
3rd Pty
3rd Pty Dev ID
0
2
×
×
×
×
×
×
×
×
3
×
×
×
×
×
×
×
×
4
×
×
×
×
×
×
×
×
5
0
0
0
0
0
0
Flag
Link
Together with the RELEASE command, this command controls exclusive access to the logical
unit (IDD) under a multi-initiator environment.
The IDD is reserved by this command for the INIT which issued this command or for some
other SCSI device specified in the CDB.
The INIT which issues this command must notify the IDD of its own SCSI ID when the
SELECTION phase is executed.. When the INIT's ID cannot be specified, this command is
terminated with a CHECK CONDITION status (ILLEGAL REQUEST [=5] / Initiator's SCSI
ID not identified [=90-00] without being executed. Also, the values specified in bytes 2 to 4
of the CDB have no meaning and are disregarded, but it is preferable that the INIT specify X
'00' in these bytes.
(1)
Logical Unit Reserve Function
This command reserves the entire IDD (logical unit) for use as a special SCSI device. The reserve
state established by this command is maintained until any one of the following conditions occurs.
1) The reserve condition is changed by the INIT that issued this command (Superseding Reserve).
2) Reserve is released by a RELEASE command from the INIT that issued this command.
3) A BUS DEVICE RESET message from any INIT.
4) A RESET condition.
5) Switching the IDD's power off or on.
When an IDD is reserved for any SCSI device, if this command is issued by an INIT that
doesn't have the "Reserve Right" for that IDD, this command is terminated with a
RESERVATION CONFLICT status. See item (3) concerning the "Reserve Right."
After the Reserved status is established, a command issued by an INIT other than the SCSI device
that reserved the IDD is rejected, except an INQUIRY, REQUEST SENSE or RELEASE command,
and a RESERVATION CONFLICT status is reported to the INIT that issued that command. The
INQUIRY and REQUEST SENSE commands are executed normally even when the IDD is
reserved for use by another SCSI device. Also, a RELEASE command is terminated with a GOOD
status, but the release operation specified in a RELEASE command issued to the IDD by a SCSI
device which does not have the Reserve Right is disregarded.