User's Guide

Chapter 3 Emulated DLT7000 SCSI Commands
Reserve Unit (16h)
254 Quantum DX-Series Software Interface Guide
Reserve Unit (16h) 3
The RESERVE UNIT command reserves the specified tape drive for
exclusive use by the requesting initiator or for another specified SCSI
device.
Table 204 RESERVE
UNIT Command
Descriptor Block -
Data Format
Bit/Byte 7 6 5 4 3 2 1 0
0
1
2-4
5
Table 205 RESERVE
UNIT Command Data
- Field Descriptions
Operation Code (16h)
Logical Unit Number 3rdPty Third Party Device ID Rsv’d
Reserved
Unused Reserved Flag (0)Link (0)
Field Name Description
3rdPty The third party reservation option for RESERVE
UNIT 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.