5.29RELEASE (10) Command (57h)

The RELEASE and the RESERVE commands are used for contention resolution in multiple-initiator systems. The RELEASE (10) command is used to release a previously reserved logical unit. The drive will not return an error if the initiator attempts to release a reservation that is not currently valid. The data format and field descriptions are shown in Table 5-157 and Table 5-158 respectively.

Table 5-157RELEASE (10) Command Descriptor Block-Data Format

Bit

7

6

5

 

4

 

3

 

2

1

0

Byte

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

Operation

Code (57h)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

Reserved

 

 

3rdPty

 

Reserved

 

LongID

Extent

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

Reservation

Identification

 

 

 

 

 

 

 

 

 

 

 

 

3

 

 

 

 

Third Party Device ID

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4 - 6

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7 - 8

 

 

 

 

(MSB)

 

 

 

 

 

 

 

 

 

Parameter List Length

 

 

 

 

 

 

 

 

(LSB)

 

 

 

 

 

9

 

 

 

 

Control

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 5-158RELEASE (10) Command — Field Descriptions

 

 

Field

Description

 

 

 

Third Party Release allows an initiator to release a logical unit that was previously reserved. If the

3rdPty

value in this field is 0, third party release is not requested. If 3rdPty = 1, then the device server will

release the specified logical unit, but only if the initiator ID, 3rdPty bit, and third party device ID

 

 

are identical when compared to the RESERVE command that established the reservation.

 

 

LongID

If the Long ID bit is set to 1, the Parameter List Length is 8 and the eight bytes of the parameter

list carry the device ID of the third party device; the contents of the Third Party Device ID in the

 

CDB (byte 3) are ignored.

 

If the Third Party Device ID value that is connected with the reservation release is smaller than

 

255, the LongID bit may be 0 and the ID value sent in the CDB. If LongID bit = 0, the Parameter

Third Party De-

List Length field also = 0. If the Third Party Device ID value is greater than 255, LongID = 1.

vice ID

Device servers that support device IDs greater than 255 will accept commands with LongID = 1;

 

 

device servers that do not support IDs greater than 255 may reject commands with LongID set =

 

1. Device ID formats are protocol-specific.

Parameter List

The contents of this field specify the length, in bytes, of the parameter list that will be transferred

Length

from the initiator to the target.

Extent

The drive supports reservations only on entire logical units. The value must be 0.

 

 

Reservation Iden-

Any value in this field is ignored by the drive.

tification

 

Note: Assuming that the RELEASE Command Descriptor Block is valid, the drive always returns a GOOD status for this command. An actual release only hap- pens if the initiator has the unit reserved for itself or a third-party initiator.

5-110 Maxtor Atlas 10K V

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Maxtor 10K V manual Release 10 Command 57h, 157RELEASE 10 Command Descriptor Block-Data Format