DSM/Tape Catalog User's Guide

Introduction to DSM/TC

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

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Tape Files

The MEDIACOM ADDTAPEFILE directive is not supported for append capable pools.

All TAPEFILEs associated with a volume set must be cataloged in the same file

catalog. TAPEFILE deletion and expiration are much the same as with ANSI and IBM

label types that contain multiple FILESEQUENCE tape file sets. When a TAPEFILE

expires or is deleted, it is marked INVALID, but it remains in the Media Catalog until all

TAPEFILEs associated with the volume set have also expired or are deleted.

Unlike ANSI and IBM tape file sets, appended TAPEFILEs residing on tape volume

sets of label type BACKUP use the associated SCSI Logical Block Address for

positioning to the beginning of the TAPEFILE, rather than the file sequence number.

The media database manager calculates an appropriate file sequence number for

appended tape files. Specifying a file sequence number in a Define for tape volumes of

label type BACKUP in an append capable pool is not necessary. If done, it must match

exactly with that chosen by the database manager, or a DSM/TC error 629 is returned.

See the DSM/Tape Catalog Management Programming Manual.

Disk Files

Although the Media Catalog accepts disk file positional information, this is unused by

Backup. Therefore Restore cannot use it to randomly locate disk files on a tape

volume.

File Catalog

A file catalog is a NonStop SQL/MP database that manages the files written to

magnetic tapes. When a file catalog is created (using the CREATE FILECAT

command), it is given a logical name in addition to the subvolume name that identifies

its physical location. A file catalog is always referred to in the DSM/TC system by its

logical name.

File catalog entries are of

ten referred to as tape file entries and disk file entries even

though both types of entries represent files stored on a tape. Every cataloged tape file

has a tape file entry, but a tape file entry for a file created by BACKUP or BACKCOPY

can have a subset of catalog entries, the result of cataloging each disk file that

comprises the tape file of a BACKUP or BACKCOPY run. BACKCOPY is a standard

Backup Restore utility. DSM/TC keeps track of which group of disk files belongs to

which backup tape file by linking all the disk file entries to the tape file entry of the

backup tape. This table lists what information is tracked by each type of file entry:

Tracked Information Tape File Entry Disk File Entry

Name of the tape file X X

Generation number of the file X X

Version number within a generation X X

Date and time when the file was written to the tape X X

Date when the tape file expires X