Tape define versus tapecatalog define usage – HP NonStop G-Series User Manual
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Introduction to DSM/TC
DSM/Tape Catalog User’s Guide — 520233-008
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The CLASS TAPECATALOG DEFINE
Access tape files that were previously cataloged
A DEFINE request specifies all the necessary information about the chosen tape file or
scratch tape by using a series of attributes. When an application opens a file requiring
an input or output tape, the information in the DEFINE is sent to $ZSVR, the operating
system tape server process. $ZSVR uses DSM/TC to verify a tape name when a name
is given in the DEFINE or asks DSM/TC to select the tape that will satisfy the
DEFINE’s request. After the tape approved by DSM/TC is mounted on a tape drive,
$ZSVR connects the application to the tape drive. For more information on $ZSVR,
see
TAPE DEFINE Versus TAPECATALOG DEFINE Usage
To use the DSM/TC system to catalog tape files, you must use TAPECATALOG
DEFINEs. If your application currently uses TAPE DEFINEs, you must convert to
TAPECATALOG DEFINEs.
With appropriate use of default values in MEDIADEFS, the minimum number of
attributes needed previously for a TAPE DEFINE decreases with TAPECATALOG
DEFINEs because many of the attributes have default values. However, there are
more attributes available for TAPECATALOG DEFINEs.
Also, DSM/TC tracks details you had to specify previously in a TAPE DEFINE. For
example, these two TAPECATALOG DEFINEs describe an input and output tape file
with only two attributes besides the CLASS attribute:
3> ADD DEFINE =READ_IN_MASTER, CLASS TAPECATALOG,&
3> & USE IN,&
3> & FILEID ACCOUNTS_PAYABLE_MASTER
7> ADD DEFINE =OUT_FILE1, CLASS TAPECATALOG,&
7> & USE OUT,&
7> & FILEID PAYROLL_CHECKS
Because the sample tape files are defined by a TAPECATALOG DEFINE, the volume
set containing the input file ACCOUNTS_PAYABLE_MASTER is automatically
retrieved by DSM/TC based on the information already in the catalog. For the output
file, PAYROLL_CHECKS, DSM/TC selects the scratch tape or tapes the file requires
and creates new catalog entries as the file is written to the volume set.
For more information on TAPECATALOG DEFINE attributes, see:
Section 6, Using TAPECATALOG DEFINE Attributes
Appendix B, CLASS TAPECATALOG DEFINE Syntax Summary
Appendix C, CLASS TAPECATALOG DEFINE Consistency Checks
Appendix D, CLASS TAPE DEFINE to CLASS TAPECATALOG DEFINE Conversion
Appendix E, CLASS TAPE/TAPECATALOG DEFINE Equivalent Attributes