SCS I Description
M axtor Atlas 10K III 5-155
The RES ERVE and the RELEASE commands are used for contention resolution in
mu ltiple-initiator systems. The RESERVE c ommand is used to reserve a logical unit.
The data format and the field descriptions are described in Table 5-186 and Table 5-
187 respe ctively.
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 initiato r ( except INQUIRY or REQUEST SENSE) is rej ected
with R ESE RV A T IO N CO NFLICT status.
0 Operation Code (16h)
1 Rese rved 3rdPty Third Party Device ID Extent
2 Res ervation Identi fication
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
Requ ired and used only whe n the 3rdPty bit is set, in which cas e this fi eld speci fies 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 occur s:
• It is superseded by another valid RESERVE command from the ini ti ator.
• It is released by the same initiator
• It is releas ed by a TARGET RESET messa ge from any in it iator.
• It is released by a hard res et condition.
The drive ignores any attempt to release the reservation made by any other initiator. For
exampl e, if ID7 sends ID2 a Third Party reservation on behalf of ID6 (the t arget at ID2
gets reserved for the initiator ID6), then only ID7 can release t he 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 reservati ons only on e nti re logical units. The val ue mus t be 0.
Reserva-
tion Iden-
tification Any value in this fie ld is ignored by the drive.
Extent
List
Length Any value in t his field is ignored by t he dri ve.