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3.1 Control/Sense Commands
C141-E167 3 -
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The RESERVE, PREEMPT, and PREEMPT AND ABORT service actions of this command
determine whether any conflict of Scope or Type specifications occurs between two reservation
requirements: the new one provided by this command, and the other one already being held on the
drive. If the reservation requirements conflict, the command is rejected and returned with the
RESERVATION CONFLICT status. In this case, RESERVE, PREEMPT, and CLEAR processing
is not executed. However, if the reservation requirement held by an initiator is preempted (specified
by the service action reservation key) in the RESERVE, PREEMPT, or PREEMPT AND ABORT
service action, the reservation requirement is excluded from the conflict determination.
The RELEASE and CLEAR service actions do not conflict with any reservation requirements.
(However, if a reservation key is not registered, or if a reservation key does not match the reserved
one, it returns the RESERVATION CONFLICT status.)
If an initiator that does not register a reservation key issues this command specified with a service
action other than REGISTER or REGISTER AND IGNORE EXISTING KEY, the command is
rejected and returned with the RESERVATION CONFLICT status.
The PERSISTENT RESERVE OUT command includes fields for specifying the type of
PERSISTENT RESERVATION service action, the applied Scope of a persistent reservation, and the
restrictions defined by a persistent reservation. For definitions of "Type" and "Scope" fields, see
Sections 3.1.18.3.1 and 3.1.18.3.2. If the specified Scope value cannot be executed on the device,
the drive returns the "CHECK CONDITION" status. The sense key is set to ILLEGAL REQUEST
[=5], and sense data is set to INVALID FIELD IN CDB [=24-00].
In fields on the PERSISTENT RESERVE OUT parameter list, information about the reservation key
and elements that are required for executing the PERSISTENT RESERVATION service action is
specified.
The parameter list is 24 bytes in length so the "Parameter List Length" field must contain "24 (18h)."
If the parameter list length is not "24 (18h)," the drive returns the CHECK CONDITION status.
Moreover, the sense key is set to ILLEGAL REQUEST [=5], and the sense data is set to
PARAMETER LIST LENGTH ERROR [=1A-00].
A logical unit uses nonvolatile memory to maintain persistent reservations and the registered keys
(even after unit power is turned off). (The AL-7 series product uses the SA space.) If the
nonvolatile memory is in the access-disabled state when the Active Persist Through Power Loss
facility is enabled (to maintain reservation requirements after unit power is turned off) by issuing the
PERSISTENT RESERVE OUT command, the drive returns the CHECK CONDITION status. The
sense key is set to NOT READY [=2], and sense data is set as defined in the TEST UNIT READY
command.
3.1.19.1 PERSISTENT RESERVE OUT service actions
To execute a service action of the PERSISTENT RESERVE OUT, the drive updates the
"Generation" value as described in the Section 3.1.18.
Table 3.3 describes the service actions of the PERSISTENT RESERVE OUT command.