Section 5 SCSI Programming Guidelines
TABLE 5-25
RESERVE
Command
Bit
7
I
6
1
5
J
4
I
3
I
2
I
1
I
0
Byte
0
OPCODE=
16H
1
LUN=O
13RDPTY
I
3RD PARTY DEVICE ID
I
EXTENT
2 RESER
VA
nON
IDENTIFICATION =
xx
34
(MSB)
EXTENT LIST LENGTH =
xx
(l.$B)
5
VU=O
I
RESERVED
=0
I
F
I
L
EXTENT • EXTENT RESER V ATION (Byte 1, Bit
0)
- Must
be
set to zero.
If
this bit
is set to one, the
ProDrive
will reject the RESERVE command with CHECK CONDITION status
with the ILLEGAL REQUEST sense key.
3RDPTY • THIRD·PARTY RESERVATION (Byte 1, Bit 4) - This is an option for the
RESERVE command that allows an initiator to reserve a logical unit for another
SCSI device.
It
is.
intended for use in multiple-initiator systems that use the
COpy
command.
5.11.12
RELEASE COMMAND: OPCODE = 17(hex)
The RELEASE command (Table 5-26)
is
used to release a previously reserVed logical unit. It is not an
error for an initiator to attempt to release a reservation that is not currently active.
TABLE 5-26
RELEASE
Command
Bit
7
I
6
I
5
J
4
J
3
J
2
J
I
1
0
Byte
0
OPCODE=
17H
1
LUN=O
13RDPTY
I
3RD PARTY DEVICE ID
I EXTENT
2
RESERV
AnON
IDENTIFICA
nON
3-4
RESERVED=O
5
VU=O
I
RESERVED=O
I
F
I
L
EXTENT • EXTENT RESERVATION (Byte 1, Bit
0)
- Must
be
set to zero.
If
this bit is
set to one, the
ProDrive
will reject the RELEASE command with CHECK CONDITION status
with the ILLEGAL REQUEST sense key.
3RDPTY - THIRD·PARTY RESERVATION (Byte 1, Bit
4)
- An option for the
RESERVE command that allows an initiator to release a logical unit that was previously reserved via
the
third-pany reservation option. It is intended for use in multiple-initiator systems that use the
COpy
command.
If
the
third-party bit is zero, the third-party release option is not requested.
If
it is
set to one, the
ProDrive
will release the specified logical unit, but only
if
the reservation was made
using the third-party reservation
option-by the same initiator for the same SCSI device specified in the
third-party device ID field.
SCSI
Programming
Guidelines
5-53
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