HP NonStop G-Series - Manual (Page 54)

DSM/TC Tape Processing
DSM/Tape Catalog User’s Guide — 520233-008
3 - 2
Labeled Tapes
emergency with the hardware at a site. If some processing is still necessary during an
emergency, you can switch to the COMPATIBLE tape support level to use TAPE
DEFINEs for tape requests.
Labeled Tapes
DSM/TC is designed to manage files stored on labeled magnetic tapes. It does not
support unlabeled tapes and their files. Some of the information about a tape and a
tape file is written in the tape’s label, and that information is duplicated in the catalog
system. With the interplay of $ZSVR, automatic volume recognition (AVR), and
DSM/TC, it is virtually impossible for a tape file to be overwritten because the operator
erroneously mounted its tape with a write-enabled ring.
Because DSM/TC keeps track of which files are on which volume sets, the file’s
generation and version numbers, and so on, all the tedious bookkeeping often done by
hand to manage tape files is eliminated.
Operator's Role in Managing Labeled Tapes
As a tape operator (any super-group user), you monitor and respond to mount
messages that appear on the tape console. Unless a specific drive is requested you
can mount the tape on any available drive to satisfy a request. You can also accept or
reject requests for the use of specific drives for unlabeled tapes or for bypassing
labeled tape processing.
Besides responding to mount and drive requests, you also initialize labeled tapes,
relabel tapes, and create scratch tapes. For more information on tape operator tasks,
see the Guardian User’s Guide.
Volume Set
A tape file is usually referred to as being written to a volume set, which comprises all
the tapes that were necessary to contain the file when it was created. A volume set can
be one, two, or several tapes. Volume sets that have more than one tape are often
referred to as multitape volume sets.
For example, two volume sets follow. The volume set for tape file NO_CAL_ACCT
includes one tape, and the volume set for SO_CAL_ACCT includes two tapes.
For a multifile volume set, two or more files are written to a volume set. DSM/TC tracks
the files on each tape in the volume set and the order in which they were written. When
a volume set consists of more than one tape, all the tapes remain assigned until all
tape file entries expire or are manually deleted.
Tape File Name Generation Tape Name
No_Cal_Acct 2 TAP102
So_Cal_Acct 3 TAP133, TAP134