DSM/Tape Catalog User's Guide
Introduction to DSM/TC
DSM/Tape Catalog User’s Guide — 520233-008
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Tape Pools
Use of multiple volume catalogs can improve Media Catalog performance.
Tape Pools
Tape pools are arbitrary divisions of a volume catalog used to group tapes by physical
characteristics, by their owners, by their users, and so on. A volume catalog can have
as many pools as you need, but it must have at least one.
Each pool name in a volume catalog must be unique. If your DSM/TC system has
more than one volume catalog, you can duplicate pool names across the volume
catalogs. For example, you could have a pool named MISC_TEST_TAPES in each
volume catalog.
A pool is created using an ADD POOL command that defines these characteristics:
The physical properties of the tapes allowed in the pool (appendable, density, label
type, open reel, or cartridge)
The status a tape should return to when its file or files expire
Whether the tape names in the pool are included in the system search space
Managing Different Types of Tape
Grouping tapes with the same physical characteristics in the same pool is an efficient
way to manage tapes at a site that uses more than one type of magnetic tape, different
types of tape label formats, and so on.
When appending tapes, put media with tape files that will expire at the same time
together to avoid tape appending fragmentation. Otherwise you could quickly end up
with no tapes available for future use.
Do not mix tapes of different physical characteristics in the same pool. This can cause
problems when an application tries to read dat
a from or write data to the tape. Unless
all applications and all tape drives can operate with every type of tape at your site, it is
possible that a tape chosen from such a pool might cause processing problems.
Tape Status After Tape Files Expire
When a tape is initially cataloged in a volume catalog and pool, its entry is given a
status of scratch. Once a file is written to a tape, its volume catalog entry is revised to a
status of assigned. When all files on the tape media expire, DSM/TC revises the tape’s
status based on the autoscratch characteristic of the tape’s pool, which allows one of
four choices:
Automatic:
Change the status to SCRATCH so the tape is immediately available as a
scratch tape.
Change the status to RELEASED to prevent the tape from being used as a
scratch tape until some future time.