Reserve (6) Command (16H) - Maxtor Atlas 10K V Product Manual

5.33

RESERVE (6) Command (16h)

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.
The data format and the field descriptions are described in Table 5-180 and Table 5-
181 respectively.
Table 5-180
Bit
Byte
0
1
2
3 - 4
5
Table 5-181
Field
3rd Pty When set to 1, it indicates that the Third Party Device ID field is valid.
Required and used only when the 3rdPty bit is set, in which case this field specifies the SCSI ID (0
through 7 only) 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• It is superseded by another valid RESERVE command from the initiator.
Third • It is released by the same initiator
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 a Third Party release). ID6 cannot release the
reservation even though the reservation was made on its behalf.
Extent The drive supports reservations only on entire logical units. The value must be 0.
Reserva-
tion Identi- Any value in this field is ignored by the drive.
fication
Extent List
Any value in this field is ignored by the drive.
Length
Note:
RESERVE (6) Command Descriptor Block-Data Format
7 6 5
Reserved
RESERVE (6) Command-Field Descriptions
The drive returns RESERVATION CONFLICT status if the unit is already
reserved for another initiator. Once the reservation is honored, any command
from another initiator (except INQUIRY or REQUEST SENSE) is rejected
with RESERVATION CONFLICT status.
4 3
Operation Code (16h)
3rdPty Third Party Device ID
Reservation Identification
Extent List Length
Control
Description
Maxtor Atlas 10K V
2 1 0
Extent
5-135