DSM/Tape Catalog User's Guide

Introduction to DSM/TC
DSM/Tape Catalog User’s Guide — 520233-008
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File Catalog
How Entries Enter the File Catalog
Entries are created in the file catalog in these ways:

A TAPECATALOG DEFINE is used to describe a new tape file. As soon as the
application begins to write data to the tape, a tape file entry is made for it.

A TAPECATALOG DEFINE is used to describe a tape file created by the BACKUP
or BACKCOPY utilities. The CATALOGFILES option of BACKUP and BACKCOPY
is used. As soon as the utility begins to write data to the tape, a tape file entry is
made that refers to the entire volume set. When a tape is full or user-defined
catalogfiles number of disk files (default 20,000 disk files) have been processed,
disk file entries are made for each disk file written to that tape. All the disk file
entries point to the tape file entry for the volume set.

The ADD TAPEFILE command is used to create a tape file entry for an existing
tape file that was not or could not be cataloged in the normal way using a
TAPECATALOG DEFINE.
All tape file and disk file entries are associated with one or more volume cat
alog
entries; this is how DSM/TC keeps track of which tape contains which file. The system
also tracks which tapes make up a volume set in the order which the tapes were used.
A volume set can be one tape, but often a volume set consists of several tapes.
How Tape File Entries Leave the File Catalog
A tape file entry is created with a retention period or expiration date. DSM/TC uses
only unexpired entries to manage tape files. Unlike volume catalog entries, tape file
entries rarely stay in the file catalog indefinitely. They come and go as the tape files are
Comment text specified in the DEFINE request X
Names of the tape media that contain the file X X
Name of the tape’s volume catalog and pool X X
Order the tapes were used if the file spans two or
more t
apes
X X
Order the file was written if more than one file was
writt
en to a volume set
X X
Tape file entry that owns the disk file entry X
Names of the tape media in a multitape volume set
tha
t contains the disk file
X
Whether the volume set is a physical or logical copy X
Caution. If the value of catalogfiles number is low whe
n backing up large number of small
files, it will hit too many catalog updates in a short period of time. This might affect the
performance of the BACKUP utility.
Tracked Information Tape File Entry Disk File Entry