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Maxtor Atlas 10K V 5-135
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 RESERVE (6) Command Descriptor Block-Data Format
Table 5-181 RESERVE (6) Command-Field Descriptions
Note: 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.
Bit
Byte
765 4 3210
0 Operation Code (16h)
1 Reserved 3rdPty Third Party Device ID Extent
2 Reservation Identification
3 - 4 Extent List Length
5 Control
Field Description
3rd Pty When set to 1, it indicates that the Third Party Device ID field is valid.
Third
Party
Device ID
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• It is superseded by another valid RESERVE command from the initiator.
• It is released by the same initiator
• It is released by a TARGET RESET message from any initiator.
• 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-
fication
Any value in this field is ignored by the drive.
Extent List
Length
Any value in this field is ignored by the drive.