Reference Guide

Chapter 4 SCSI Commands
PERSISTENT RESERVE OUT Command (5Fh)
DLT-S4 Interface Reference Guide 224
04h Preempt A PERSISTENT RESERVE OUT command with a successful Preempt service action
removes all persistent reservations for all initiators that have been registered with
the service action Reservation Key specified in the
PERSISTENT RESERVE OUT
command’s parameter list. A persistent reservation is also established for the
preempting initiator. Any commands from any initiator that the drive has accepted
as non-conflicting continue their normal executions. If an initiator sends a
PERSISTENT RESERVE OUT command that specifies a Preempt service action and
no persistent reservation exists for the initiator identified by the service action
Reservation Key, it is not an error condition.
A
UNIT ATTENTION condition is established for the preempted initiators. The Sense
Key is set to
UNIT ATTENTION; the Additional Sense Code is set to RESERVATIONS
PREEMPTED
. Commands that follow are subject to the persistent reservation
restrictions set by the preempting initiator.
The persistent reservation the preempting initiator created is defined by the Scope
and Type fields of the
PERSISTENT RESERVE OUT command and the
corresponding fields of the command’s parameter list.
The Preempt service action removes the registration keys for the preempted
initiators; the Reservation Key for an initiator that has performed a Preempt
service action with its own Reservation Key specified in the service action
Reservation Key remains unchanged, although all other specified releasing actions
and reservation actions are performed.
Note that persistent reservations are not superseded by a new persistent
reservation from any initiator except by the execution of a
PERSISTENT RESERVE
OUT
command that specifies either the Preempt or the Preempt & Abort service
actions. New persistent reservations that do not conflict with an existing persistent
reservation execute normally.
Code Name Description