Datasheet

4.1 Control/Sense Commands
C141-C008 4-83
(2) Reserve right and third party reserve function
The third party reserve function is not supported by the drive.
If the "3rd Pty" bit in byte 1 of the CDB is "0," the IDD is reserved by the INIT
which issued this command and that INIT has the Reserve right for the IDD.
If the "3rd Pty" bit is "1," the third party reserve function is specified. An INIT
which specifies the third party reserve function and issues this command can
reserve the IDD for use by another FC device. In this case, this command
reserves the IDD for the device (called the third party device) with the ALPA
specified in the "3rd Pty FC Dev ID" field in byte 1 of the CDB. Even if the IDD
is reserved for another FC device using the third party reserve function the reserve
right for that ID resides with the INIT that issued this command. Therefore, in
order to release that reserve state, it is necessary for the INIT that issued this
command to issue a RELEASE command (shown in Section 4.1.12) with the third
party release function specified. Also, the conditions for maintaining the reserve
state established by the third party reserve function are the same as in the case
where the third party reserve function is not used. (See item (1).)
(3) Changing the reserve conditions (Superseding Reserve)
The INIT which has the reserve right for an IDD (the INIT which has issued this
command in the past and has established the IDD reserve state) can change the
IDD's reserve conditions by issuing a another RESERVE command (Superseding
Reserve).
When a superseding reserve is executed, the IDD releases the reserve state it was
in up to that point and establishes a new reserve state in accordance with the
specifications in this newly issued command.
By using this function, the INIT can, for example, change the FC device (ALPA)
for which the logical unit is reserved while continuing the reserve state of the
logical unit with which the reserve state was established using the previous third
party reserve function.