Maxtor ATLAS 10K III - Manual (Page 164)

SCSI Description
5-100 Maxtor Atlas 10K III
04h Pre-empt
A PERSISTENT RESERVATION OUT command with a successful Pre-empt ser-
vice action removes all persistent reservations for all initiators that have been
registered with the Service action Reservation key specified in the PERSISTENT
RESERVATION OUT command’s parameter list. A persistent reservation is also
established for the pre-empting initiator. Any commands from any initiator that
have been accepted by the device server as non-conflicting continue their nor-
mal executions. If a PERSISTENT RESERVATION OUT command is sent that
specifies a Pre-empt service action and no persistent reservation exists for the
initiator identified by the Service action Reservation key, it is not an error con-
dition.
A UNIT ATTENTION condition is established for the pre-empted initiators. The
sense key is set to UNIT ATTENTION; the additional sense data is set to RES-
ERVATIONS PREEMPTED. Commands that follow are subject to the persistent
reservation restrictions set by the pre-empting initiator.
The persistent reservation thus created by the pre-empting initiator is defined
by the Scope and Type fields of the PERSISTENT RESERVATION OUT com-
mand and the corresponding fields of the command’s parameter list.
The registration keys for the pre-empted initiators are removed by the Pre-empt
service action; the reservation key for an initiator that has performed a Pre-
empt service action with its own Reservation key specified in the Service action
Reservation key remains unchanged, although all other specified releasing ac-
tions and reservation actions are performed.
Note that persistent reservations are not superseded by a new persistent res-
ervation from any initiator except by the execution of a PERSISTENT RESER-
VATION OUT that specifies either the Pre-empt or the Pre-empt and Clear
service actions. New persistent reservations that do not conflict with an exist-
ing persistent reservation execute normally. The persistent reservation of a log-
ical unit or extents having the same Type value are permitted if no conflicting
persistent reservations other than the reservations being pre-empted are held
by another initiator.
Note: Service Action (Code) 4 is not supported by Atlas 10K III.
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