HP NonStop G-Series - Manual (Page 45)

Tape File Concepts
DSM/Tape Catalog User’s Guide — 520233-008
2 - 5
Tape File Version
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