Superseding Reservations

An initiator that currntly has a logical unit reserved may modify the current reservation by issuing another RESERVE UNIT command to the same logical unit. The superseding reservation shall release the current reservation if the superseding reservation request is granted.

If the superseding resrvation cannot be granted because of conflicts INTERFACE with a previous reservation (other than the current reservation), then

the target shall return RESERVATION CONFLICT status.

See ANSI SCSI-2 9.2.10.2 for details.

RELEASE UNIT Command

The RELEASE UNIT command (Table 3.9) is used to release previously reserved logical units for the requesting initiator to another specified SCSI device.

Table 3.9 RELEASE UNIT Command

Bit

7

6

5

4

3

 

2

1

0

Byte

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

Operation Code (17h)

 

 

 

 

 

 

 

 

 

 

 

 

1

Logical Unit Number

3rdPty

Third Party Device ID

Reserved

 

 

 

 

 

 

 

 

 

 

2

 

 

 

Reserved

 

 

 

3

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

5

 

 

 

Control

 

 

 

The RESERVE UNIT and RELEASE UNIT commands provide the basic mechanism for contention resolution in multiple-initiator systems.

If a valid reservation exists for the I_T_L nexus, the target shall release the reservation and return GOOD status.

M3099GX/GH OEM Manual

3-31