7DQGEHUJ'DWD 6&6,&RPPDQGV
7DQGEHUJ'/73URGXFW0DQXDO 
5(6(59(81,7&RPPDQGKFRQWLQXHG
)LHOG1DPH 'HVFULSWLRQ
3rdPty The third party reservation option for RESERVE UNIT (6) allows an
initiator to reserve a logical unit for another SCSI device. This option is
intended for systems that use COPY, and is implemented by the tape
drive.
If set to 1, logical unit is reserved for the SCSI device whose ID appears
in the Third Party Device ID field. The tape drive ignores any attempt
made by any other initiator to release the reservation and returns a
GOOD status.
If set to 0, no third party reservation is requested and device is reserved
for the initiator that issued the CDB.
Third Party
Device ID If 3rdPty is set to 1 (indicating that an initiator has reserved the logical unit
for another SCSI device), this field contains the ID number of that SCSI
device for which the reservation was made.
7DEOH±5(6(59(81,7&RPPDQG'DWD²)LHOG'HVFULSWLRQV
A reservation via the RESERVE UNIT (6) command remains in effect until one of
the following conditions is met:
• The initiator that made the reservation sends another RESERVE UNIT (6)
command.
• The tape drive is released via a RELEASE UNIT (6) command from the
same initiator.
• A BUS DEVICE RESET message is received from any initiator.
• A hard reset occurs.
The occurrence of the last two conditions is indicated by the drive returning a
CHECK CONDITION status, sense key of UNIT ATTENTION on the next
command following the condition. It is not an error to issue a RESERVE UNIT (6)
command to a drive that is currently reserved by the requesting initiator.
If the logical unit has previously been reserved by another initiator, the target
returns a RESERVATION CONFLICT status.
If, after honoring the reservation, any other initiator attempts to perform any
command except INQUIRY, REQUEST SENSE, or RELEASE UNIT (6), the
command is rejected with a RESERVATION CONFLICT status. A RELEASE
UNIT (6) command issued by another initiator is ignored by that logical unit.