5190/5194 Modular Tape Subsystem Manual

Operating the Cartridge Tape Drive and ACL
5190/5194 Modular Tape Subsystem Manual—426878-002
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Using a DEFINE to Override the Systemwide
Compression Default Setting
•
If no systemwide default compression setting was set using the ALTER
MEDIADEFS command, the default compression setting for any tape in a 5190
drive is off.
•
Applications specifying a CLASS TAPE DEFINE always use the systemwide
default compression setting for compression, because there is no COMPRESSION
attribute for a CLASS TAPE DEFINE.
Examples
All examples assume that you are not using DSM/TC. Examples 1 and 2 show CLASS
TAPECATALOG DEFINEs specified for BACKUP operations.
Example 1
This example for a labeled tape specifies a CLASS TAPECATALOG DEFINE named
“=BACK” with compression on (IDRC). The USE OUT attribute specifies to write the
file to tape.
The BACKUP command copies all the files in the $DATA volume to tape. The LISTALL
option lists the names of all files backed up, and the NOUNLOAD option directs
BACKUP to rewind the final tape and leave it online when the BACKUP operation is
complete.
1>ADD DEFINE =BACK, CLASS TAPECATALOG, LABELS BACKUP,&
1>&CATALOG OFF, COMPRESSION IDRC, USE OUT
2>BACKUP =BACK, $DATA.*.*, LISTALL, NOUNLOAD
Example 2
This example for an unlabeled tape specifies a CLASS TAPECATALOG DEFINE
named “=UNLABEL” with compression off. For unlabeled tape, you must specify a
device in the DEFINE (in this example, DEVICE $TAPE1). Because it is an unlabeled
tape, the LABELS attribute has the value OMITTED.
3>ADD DEFINE =UNLABEL, CLASS TAPECATALOG,&
3>&LABELS OMITTED, CATALOG OFF, DEVICE $TAPE1, COMPRESSION OFF
4>BACKUP =UNLABEL, $DATA.*.*, LISTALL, NOUNLOAD
Example 3
This example for an unlabeled tape shows a BACKUP command that does not use a
DEFINE. In this case, the tape drive writes data using the systemwide default
compression setting.
5>BACKUP $TAPE, $DATA.*.*