DSM/Tape Catalog User's Guide

DSM/Tape Catalog User’s Guide — 520233-008
9 - 1
9 Database Design of DSM/TC
This section describes the design of the DSM/TC catalog database:
DSM/TC Catalog Database
DSM/TC uses audited SQL/MP tables to archive the file and volume catalog
information. SQL/MP provides excellent query and reporting tools for use by third
parties and users, and provides data independence through views.
The DSM/TC catalog database consists of two catalogs:

The volume catalog contains the information related to tape volumes, including
pools, tape volumes in each pool, and pool constraints.

The file catalog stores information on tape files and disk files, and provides a
mapping from those files to the tape volumes that contain them.
The volume and file catalog tables are located in an SQL catalog subvolume. DSM/TC
information can be stored in an existing SQL catalog subvolume, or you can create a
new SQL catalog specifically for DSM/TC. Both catalogs are created with a physical
location and a logical name. Users reference catalogs by their logical names in a
CLASS TAPECATALOG DEFINE, and DSM/TC tracks where the catalogs reside.
The DSM/TC database is active. It is updated immediately whenever a
new tape
volume is written. The database accurately reflects the data present on tape volumes.
For more information on SQL/MP topics, see the SQL/MP Reference Manual.
Locating Tape Files
The DSM/TC database contains all of the information needed to locate a tape file
based on the tape file’s ID. For example, applications open a file on tape by specifying
the file ID in a TAPECATALOG DEFINE. The system consults DSM/TC to locate the
tape volume containing the tape file, ensures the tape volume is mounted on an
unassigned tape drive, assigns the drive to the application, and positions the tape at
the correct backup job on the appendable media if the media is appendable.
Topic Page
DSM/TC Catalog Database 9-1
File Catalog Tables and Structures 9-5
Volume Catalog Tables and Structures 9-11
Shorthand Views 9-14
Sizing Estimate for the DSM/TC Database 9-15