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SCSI Commands

5-152 Quantum DLT 8000 Tape System

PERSISTENT RESERVATION OUT Command (5Fh) (continued)

Table 5–67 PERSISTENT RESERVATION OUT Command’s Service Action

Descriptions (continued)

Code Name Description

04h Pre-

empt

A PERSISTENT RESERVATION OUT command with a successful Pre-empt service

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 normal 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 condition.

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 RESERVATIONS

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 command 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 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Note that persistent reservations are not superseded by a new persistent reservation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 RESERVATION OUT that

specifies either the Pre-empt or the Pre-empt and Clear service actions. New

persistent reservations that do not conflict with an existing persistent reservation

execute normally. The persistent reservation of a logical 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.

(continued)

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Quantum DLT 8000 Handbuch Seite 296