RESERVE UNIT Command

The RESERVE UNIT command (Table 3.8) is used to reserve logical unit for the exclusive use of the requesting initiator to another specified SCSI device.

Table 3.8 RESERVE UNIT Command

Bit

7

6

5

4

3

 

2

1

0

Byte

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

Operation Code (16h)

 

 

 

 

 

 

 

 

 

 

 

 

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.

This command requests that the entire logical unit be reserved for the exclusive use of the initiator until the reservation is superseded by another valid RESERVE UNIT command from the initiator that made the reservation or until released by a BUS DEVICE RESET message from any initiator, by a hard reset condition, or by a power on cycle. The reservation shall not be granted if the logical unit is reserved by another initiator. It shall be permissible for an initiator to reserved a logical unit that is currently reserved by that initiator.

If the logical unit is reserved for another initiator, the target shall return RESERVATION CONFLICT status.

3rdPty:0b (Reserved)

Third Party Device ID: 000b (Reserved)

3-30

M3099GX/GH OEM Manual