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SCSI Description
Maxtor Atlas 10K III 5-155
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 5-186 and Table 5-
187 respectively.
RESERVE (6) Command Descriptor Block-Data Format
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.
0 Operation Code (16h)
1 Reserved 3rdPty Third Party Device ID Extent
2 Reservation Identification
3 - 4 Extent List Length
5 Control
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• It is superseded by another valid RESERVE command from the initiator.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 Iden-
tification
Any value in this field is ignored by the drive.
Extent
List
Length
Any value in this field is ignored by the drive.