Quantum 10K II - Manual (Page 194)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–127
PERSISTENT RESERVATION OUT Command (5Fh) (continued)
Table 5–59 PERSISTENT RESERVATION OUT Command’s Service Action
Descriptions (continued)
Code Name Description
01h Reserve A PERSISTENT RESERVATION OUT command with Reserve service action
creates a persistent reservation with a specified Scope and Type.
Persistent reservations are not superseded by a new persistent reservation
from any initiator except by the execution of a PERSISTENT RESERVATION
OUT command that specifies either a Pre-empt or Pre-empt and Clear
service action. New persistent reservations that do not conflict with an
existing persistent reservation execute normally. Persistent reservations of
logical units or extents having the same Type value are permitted if no
conflicting persistent reservations are held by another initiator. When these
types of overlapping reservations are released, each of the extent
reservations and logical unit reservations are removed with a separate
Release service action. Multiple identical reservations from the same
initiator are all released simultaneously via a single Release service action
that matches the reservations.
02h Release A PERSISTENT RESERVATION OUT command with Release service action
removes a persistent reservation held by the same initiator.
The fields associated with a Release service action match fields of the
active persistent reservation. Sending of a PERSISTENT RESERVATION OUT
command that specifies a Release service action when no persistent
reservation exists from that initiator does not result in an error. Instead, the
device server returns a GOOD message without altering any other
reservation: the reservation key is not changed by the Release service
action.
The device server returns a CHECK CONDITION status for any PERSISTENT
RESERVATION OUT command that specifies the release of a persistent
reservation held by the requesting initiator that matches some but not all
of the Scope, Type, Reservation Key, and extent values. The sense key is set
to ILLEGAL REQUEST and additional sense data is set to INVALID RELEASE
OF ACTIVE PERSISTENT RESERVATION. Attempts to release persistent
reservations in which none of the Scope, Type, Reservation Key, and extent
values match an existing persistent reservation held by the initiator making
the request are not errors.
An active persistent reservation may also be released by:
• Powering off. When the most recent APTPL value received by the
device server is 0, a power-off performs a hard reset, clears all
persistent reservations, and removes all registered reservation keys;
or
• Executing a PERSISTENT RESERVATION OUT command from another
initiator with a persistent reserve service action of Pre-empt or Pre-
empt and Clear.
Note that a Release service action should not be performed if any
operations interlocked by the persistent reservation have not yet
completed.
(continued)