IBM Ultrastar 36LZX Specifications page 132

Reserve This service action does not conflict with a successfully established persistent reservation.
If the initiator has not previously performed a Register service action, the command
with this service action is rejected with RESERVATION CONFLICT status.
If the key specified in the Reservation key field is already registered but the initiator
which registered the key is different from the initiator requesting the command, the
target returns RESERVATION CONFLICT status.
If persistent reservation that is being attempted conflicts with persistent reservation
that is held, the target returns a RESERVATION CONFLICT status.
The established persistent reservation applies to all commands received after the
successful completion of the command.
Release This service action may conflict with a successfully established persistent reservation.
If the initiator requesting the command has not previously performed a Register
service action, the command is rejected with a status of RESERVATION CONFLICT
status.
If the key specified in the Reservation key field is already registered but the initiator
which registered the key is different from the initiator requesting the command, the
drive returns a RESERVATION CONFLICT status.
The drive returns GOOD status when a key specified in Reservation key field is not
found.
When the key is found but the scope is different from the registered scope or the type
is different from the registered type, the command is rejected with CHECK
CONDITION status. The sense key is set to ILLEGAL REQUEST and the additional
sense data is set to INVALID RELEASE OF ACTIVE PERSISTENT RESERVATION.
Ultrastar 36LZX hard disk drive specifications
132