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5.24 RESERVE:(16
Bit
Byte
0
1
Logical Unit Number
2
3
4
5
Vendor Unique
The RESERVE command reserves a logical unit for the host computer issuing this
command. The third-party reservation feature allows the logical unit to be reserved
for another specified SCSI device.
The RESERVE and RELEASE commands provide the basic mechanism for resolving
contentions that can occur in multi-host (initiator) systems.
Since this SCSI controller does not support the extended reservation feature, the
Extent bit must always be set to 0. If this is not observed, the controller creates the
CHECK CONDITION status with ILLEGAL REQUEST sense key.
The controller ignores the Reservation Identification and Extent List Length fields
that are used by the extent reservation feature. Accordingly, no Data Out phase can
occur.
(1) Logical unit reservation
The RESERVE command requests the controller to reserve the specified logical
unit so that the host computer can use the entire logical unit exclusively until
the reservation is superseded by another valid RESERVE command issued by
the same host computer or until the reservation is released by a RELEASE
command from the same host computer, by a Bus Device Reset message from
another host computer, or by a hardware reset.
A logical unit reservation is rejected with the RESERVATION CONFLICT
status set if the specified logical unit has already been reserved by another host
computer.
controller (the RESERVE command itself is queued, however).
RESERVE:(16h)
5 COMMAND DESCRIPTIONS
)
H
7
6
5
0
0
0
Reservation Identification
Extent List Length (MSB)
Extent List Length (LSB)
0
0
0
In this case, the reservation request is not queued into the
4
3
Operation Code (16
H
1
0
3rdPty
Third Party Device ID
Reserved
0
0
OEM MANUAL:K6602924
2
1
)
1
1
Extent
Flag
Link
0
Revision: 1 / Date: 2003.03.06
Page: 224 / 273
0
0
0
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