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3.1 Control/Sense Commands
C141-E167 3 -
59
For the "Reservation Key" field, an 8-byte key code provided by the application client is set in order
to enable the drive to identify the initiator that is the source of the PERSISTENT RESERVE OUT
command. The drive can then verify that the "Reservation Key" field in the PERSISTENT
RESERVE OUT command matches the registered reservation key for the initiator that issues the
command. However, if the reservation key value is zero, which means no reservation key is
registered, the specified value in this field is ignored. If the key specified for the PERSISTENT
RESERVE OUT command does not match the registered reservation key for the initiator, the drive
returns the RESERVATION CONFLICT status. This reservation key of the initiator is valid to all
service actions and Scopes.
The "Service Action Reservation Key" field must be specified for the REGISTER, PREEMPT, and
PREEMPT AND ABORT service actions. In the REGISTER service action, a new registered
reservation key is specified in this field. In the PREEMPT and PREEMPT AND ABORT service
actions, a reservation key of the initiator that holds the reservation requirements to be preempted is
specified in this field. In the PREEMPT or PREEMPT AND ABORT service actions, if the value
specified in this field does not match any registered reservation key, the drive returns the
RESERVATION CONFLICT status. In other service actions, the value specified in this field is
ignored.
If the Scope is the Element reservation, the "Scope-specific Address" field contains the Element
address, zero filled in the most significant bytes to fit the field. If the service action is REGISTER,
REGISTER AND IGNORE EXISTING KEY, or CLEAR, or if the Scope is a Logical Unit
reservation, the "Scope-specific Address" field is set to zero.
The "Activate Persist Through Power Loss (APTPL)" bit shall be valid only for the REGISTER
service action. In any other service action, the APTPL bit is ignored. Support for the APTPL bit is
optional. If a value is specified for a drive that does not support the APTPL bit, the drive returns the
CHECK CONDITION status and terminates this command. In this case, the sense key is set to
ILLEGAL REQUEST [=5], and sense data is set to INVALID FIELD IN PARAMETER LIST [=26-
00].
If the last APTPL bit value received by the driver is zero, all persistent reservations are released and
all reservation keys are cleared by turning off the power to the target (See Section 4.2.1.1). If the
last APTPL bit value received by the driver is one, the logical unit keeps all persistent reservations
and reservation keys for all initiators even after unit power is turned off once and turned on again.
(MA*3*** series product saves the registration information in the SA space.) The APTPL value
controls the operation of the logical unit while power is off, and it is always valid even if it is
received from an initiator.
Table 3.4 summarizes which fields are defined by the application client and interpreted by the drive
for each service action and scope value. The reservation keys and APTPL are explained in previous
sections.