DSM/Tape Catalog User's Guide

Tape File Concepts

DSM/Tape Catalog User’s Guide — 520233-008

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Tape File Version

A version of a tape file can be viewed as a subdivision of a generation. Usually, there is

only one version of a tape file entry. But if there is any problem with the existing tape

file, you could instruct the operator to revise the output tape DEFINE before rerunning

the application so that a new version is made instead of a new generation.

DSM/TC lets only one version in a generation be valid—the latest version entered in

the file catalog. You never have to specify which version you want for an input tape file

because DSM/TC recognizes only the valid version as the correct one.

Example

Your application uses this DEFINE to request the output tape file each time it runs:

15> ADD DEFINE =OUT, CLASS TAPECATALOG,&

15> & LABELS ANSI,&

15> & FILEID MASTER_OUT,&

15> & VOLUME SCRATCH,&

15> & POOL MKT_TAPES,&

15> & USE OUT,&

15> & GEN +1

On the day your application writes the third generation of MASTER_OUT, it fails half

way through. DSM/TC creates a tape file entry for generation 3 of MASTER_OUT that

represents an incomplete tape file. Before rerunning the application, the operator

changes the =OUT DEFINE to:

16> ADD DEFINE =OUT, CLASS TAPECATALOG,&

16> & LABELS ANSI,&

16> & FILEID MASTER_OUT,&

16> & VOLUME SCRATCH,&

16> & POOL MKT_TAPES,&

16> & USE OUT,&

16> & GEN 3,&

16> & VERSION NEW

Because the GEN attribute specifies an existing generation in the catalog, and the

VERSION attribute is NEW, DSM/TC creates a new version of generation 3 for

MASTER_OUT. It takes two reruns before the application completes successfully. The

file catalog has these entries for MASTER_OUT:

There are three versions of MASTER_OUT in generation 3. Only the third version is

valid for that generation of MASTER_OUT. (Although the preceding chart shows all

File Name Date Created Absolute Generation Version Version Status

MASTER_OUT Feb 12 1 0 Valid

MASTER_OUT Feb 19 2 0 Valid

MASTER_OUT Feb 26 3 0 Invalid

MASTER_OUT Feb 26 3 1 Invalid

MASTER_OUT Feb 26 3 2 Valid