Maxtor 10K V - Manual (Page 144)

5-86 Maxtor Atlas 10K V
05h
Pre-empt &
Clear
A PERSISTENT RESERVATION OUT command with a Pre-empt & Clear service action
removes all persistent reservations for all initiators that have been registered with the Ser-
vice action Reservation key specified in the PERSISTENT RESERVATION OUT com-
mand’s parameter list. It also establishes a persistent reservation for the pre-empting
initiator. Any commands from the initiators being pre-empted are terminated as if an
ABORT TASK management function had been performed by the pre-empted initiator. If a
PERSISTENT RESERVATION OUT command is sent that specifies a Pre-empt & Clear
service action and no persistent reservation exists for the initiator identified by the Service
action Reservation key, it is not an error condition. If the key is registered, however, the
Clear portion of the action executes normally.
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 PRE-
EMPTED. Commands that follow, and retries of commands that timed out because there
were cleared are subject to the persistent reservation restrictions set by the pre-empting ini-
tiator.
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 correspond-
ing fields of the command’s parameter list.
The Pre-empt & Clear service action clears any ACA or CA condition associated with the
initiator that is pre-empted and clears any tasks with an ACA attribute from that initiator.
Any Asynchronous Event Reporting operations in progress that were initiated by the device
server are unaffected by a Pre-empt and Clear service action.
The reservation key for the other initiators pre-empted are removed by the Pre-empt & Clear
service action. The reservation key for an initiator that has sent a Pre-empt & Clear action
with its own reservation key specified in the service action’s reservation key remains un-
changed, although all other specified clearing actions, releasing actions, and reservation ac-
tions are performed.
Persistent reservations are not superseded by a new persistent reservation from any initiator
except via execution of a PERSISTENT RESERVATION OUT that specifies either the Pre-
empt or Pre-empt & Clear service action. New persistent reservations not in conflict with an
existing persistent reservation execute normally. The persistent reservation of a logical unit
or extent that has the same Type value is permitted as long as no conflicting persistent res-
ervations other than the reservations being pre-empted are permitted.
Code Name Description