Operating instructions

20-2
SCSI REFERENCE 1012975
CHAPTER 20—RESERVE (16h OR 56h)
20.1 ABOUT THIS COMMAND
The RESERVE command allows the initiator to perform two types of
reservations:
 Unit reservation — reserves the autoloader as a whole.
 Element reservation — reserves specific elements of the autoloader,
including storage elements (the cartridge cells) and the tape drive.
The autoloader supports both the six-byte and the ten-byte format of the
RESERVE UNIT CDB. The autoloader determines which version of the
command is being used based on the operation code in the CDB. You can use
either version of the command, with the following qualifications:
 Individual elements can only be reserved using the six-byte RESERVE CDB.
 A 3rd-party reservation can only be made using the ten-byte RESERVE CDB.
 Either version of the RESERVE CDB can be used to reserve the autoloader
as a unit.
Reservations can be released with a RELEASE (17h or 57h) command from the
same initiator (see Section 17.1 on page 17-2), a reset, or a power-on of the
autoloader.
To modify or supersede a previous element reservation, issue a RESERVE
command with the same Reservation Identification. If the superseding
reservation does not result in any reservation conflicts or error conditions, the
autoloader releases the previous reservation and completes the new
reservations. A unit reservation of the autoloader will supersede any previous
element reservations by the same initiator.
Notes:
 If the autoloader is reserved as a unit, the autoloader processes only the
following commands from another initiator:
 INQUIRY
 RELEASE
 REQUEST SENSE
 PREVENT/ALLOW MEDIUM REMOVAL with Prevent=00b
All other commands result in a Reservation Conflict (18h) status.
 If an initiator has reserved at least one element, another initiator cannot do the
following:
 Issue a MODE SELECT command that changes any element addresses. If the
autoloader receives such a command, it returns a Reservation Conflict (18h)
status to the initiator.
 Move a cartridge to or from that element.
 Position the cartridge loader to that element.
 Issue a WRITE BUFFER command to load new flash code.