User's Guide

Chapter 3 Emulated DLT7000 SCSI Commands
Reserve Unit (16h)
Quantum DX-Series Software Interface Guide 255
A reservation via the RESERVE UNIT command remains in effect until
one of the following conditions is met:
The initiator that made the reservation sends another RESERVE UNIT
command.
The tape drive is released via a RELEASE UNIT 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 command to a drive that is currently
reserved by the requesting initiator.
If another initiator has previously reserved the logical unit, the target
returns a RESERVATION CONFLICT status.
Flag Bit The Flag bit is used in conjunction with the Link bit
to notify the initiator in an expedient manner that a
command has been completed.
Flag bits are not supported by the DX-Series system.
Link Bit A Link bit set to 1 indicates that the initiator
requests continuation of a task (an I/O process)
across two or more SCSI commands.
If the Link bit is 1 and the Flag bit is 0, and the task
completes successfully, the drive continues the task
and returns a status of INTERMEDIATE and a
LINKED COMMAND COMPLETE message.
If the Link bit and the Flag bit within a Control
word are both set to 1, and the drive completes a
command with a status of INTERMEDIATE, the
drive returns a LINKED COMMAND COMPLETE
message (with Flag).
Link bits are not supported by the DX-Series
system.
Field Name Description