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4.1 Control/Sense Commands
C141-C013 205
The specification of the "Service Action Reservation Key" field is necessary for the
REGISTER, PREEMPT, and PREEMPT and ABORT Service Actions. For the
REGISTER Service Action, a Reservation Key to be newly registered is set in this
field. For the PREEMPT and, PREEMPT and ABORT Service Actions, the
Reservation Key of the INIT that holds a reserve condition to be cleared (preempted) is
set in this field. For the PREEMPT and, PREEMPT and ABORT Service Actions, if
the value specified in this field does not match any of the Reservation Keys registered,
the drive reports the RESERVATION CONFLICT status. For the Service Actions
listed below, the value specified in this field is ignored.
When the Scope value indicates Element Reservation, an element address (with the
high byte filled with zeroes) is set in the Scope-specific Address field. If the Service
Action is REGISTER, REGISTER and IGNORE EXISTING KEY, or CLEAR, or if
the Scope indicates LU Reservation, set zero in the Scope-specific Address field.
The Activate Persist Through Power Loss (APTPL) bit is valid only for the
REGISTER Service Action. For the other Service Actions, this bit is ignored. The
support of the APTPL bit is optional, and if this bit is set for a drive that does not
support this bit, the drive terminates this command with the CHECK CONDITION
status. At this time, the sense key is set to ILLEGAL REQUEST [= 5], and the
sense data is set to INVALID FIELD IN PARAMETER LIST [= 26-00].
If the value of the APTPL bit that is last received by the drive is '0,' the power
shutdown of the TARG releases all the PERSISTENT RESERVATIONs and
clears all the Reservation Keys. If the value of the APTPL bit that is last received
by the drive is '1,' the logical unit maintains all the PERSISTENT
RESERVATIONs and Reservation Keys for all the INITs throughout power
shutdown and re-power-on sequences (the SA space is used to save the
registration information). The APTPL value, which controls the logical unit
behavior while the power is turned off, is valid regardless of which INIT the bit
value has been received from.
Table 4.32 explains which fields are set by an application client and how such
fields are recognized by a drive as regards each Service Action and Scope value.
As for Reservation Keys and APTPL, they are as explained above.