
2–6
StorageWorks SDLT Tape Drive by Compaq Reference Guide
Operating System Device Drivers
Example 2
Another example to turn on compression using a tar command is:
$tar cvf /dev/tape/tape5c filename.txt
Where:
•
tape5 = the tape device as known by the system (shown in the file command, in
this case, tape unit 5).
•
c = compression on.
Turning Compression Off
The following command turns hardware compression off:
$tar cvf /dev/tape/tape5 filename.txt
For the latest UNIX patches refer to:
www.support.compaq.com/patches/
Open VMS
The OpenVMS operating system uses native SCSI recognition for locally attached
SCSI drives, which allows the operating system to recognize the SDLT drive.
Recognition of the SDLT drive allows non-default settings, such as the density setting,
to be used.
SCSI recognition for the SDLT drive is not supported for SCSI drives on any client
node in an OpenVMS cluster that is running version 7.2-1 or earlier. If the SDLT drive
is served to such a client that client system defaults to a generic SCSI device and the
default settings are used.
The SDLT drive provides compression (called compaction in OpenVMS terminology)
so that the storage capability for tapes can be effectively doubled when the SDLT drive
has been instructed to turn on compaction. This is known as hardware compaction and
should be used instead of the software compaction that is sometimes provided by
software products. The SDLT drive is instructed by the user to turn on hardware
compaction through use of the OpenVMS
INITIALIZE
and
MOUNT
commands. (See these
two commands using Open VMS help from the $ prompt).
The format for the
INITIALIZE
command is:
INITIALIZE
/MEDIA_FORMAT
/MEDIA_FORMAT=[NO]COMPACTION