Maxtor 10K III manual Reserve 10 Command Descriptor Block-Data Format

SCSI Description

￿￿￿￿4'5'48'￿￿￿￿￿￿%QOOCPF￿￿￿￿J￿The RESERVE and the RELEASE commands are used for contention resolution in multiple-initiator systems. The RESERVE command is used to reserve a logical unit. If RESERVE (10) is used, then RELEASE (10) is also used. The data format and the field descriptions are described in Table 5-188and Table 5-189respectively. The data format for the Event Descriptors is described in Table 5-190.

RESERVE (10) Command Descriptor Block-Data Format

0

Operation Code (56h)

1

Reserved

3rdPty

Reserved

LongID

Extent

2

Reservation Identification

3

Third Party Device ID

- 6

Reserved

7 -

(MSB)

Parameter List Length

(LSB)

9

Control

$[VG$KV

￿

￿RESERVE￿

(10) Command￿

-Field￿Descriptions￿

￿

￿

3rd(KGNFPty

When set to 1, it indicates that the Third&GUETKRVKQPParty Device ID field is valid.

When 0, indicates that the third party device associated with the reservation release

LongID

has number smaller than 255 and the ID value can be sent within the CDB. If set

= 1, indicates that the third party device ID is greater than 255, the ID value within

Tablethe5CDB-188is ignored, and the parameter list length is at least eight.

Required and used only when the 3rdPty bit is set, in which case this field specifies

the SCSI ID of the initiator to be granted the reservation of the logical unit. The drive

preserves the reservation until one of the following occurs:

• It is superseded by another valid RESERVE command from the initiator.

• It is released by the same initiator.

Third Party

• It is released by a TARGET RESET message from any initiator.

Device ID

• It is released by a hard reset condition.

The drive ignores any attempt to release the reservation made by any other initiator.

For example, if ID7 sends ID2 a Third Party reservation on behalf of ID6 (the target

at ID2 gets reserved for the initiator ID6), then only ID7 can release the target at ID2

(using Third Party release). ID6 cannot release the reservation even though the res-

ervation was made on its behalf.

If 0, requests that the entire logical unit be reserved for use only by the initiator until

the request is supplanted by another valid RESERVE command from the same initia-

tor, or until released via a RELEASE (10) command from the reserving initiator, a hard

reset,Tableor

5a-power189

on cycle.

If set = 1, the extent reservation option is implemented. This option allows an ap-

Extent

plication client in a multitasking environment to have multiple reservations.

The size of the extent list is defined by the contents of the Parameter List Length field. The extent list consists of zero or more descriptors. Each descriptor defines an extent beginning at the specified logical block address for the specified number of blocks. If the number of blocks is 0, the extent begins at the specified logical block address and continues through the last logical block address on the logical unit. The data format of extent descriptors is shown in Table 5-190.

5-156 Maxtor Atlas 10K III