Technical data

Using BACKUP
11.11 Understanding Multivolume BACKUP Operations
11.11 Understanding Multivolume BACKUP Operations
When you save data with BACKUP, the save set often spans more than one
volume, creating a multivolume save set. When this occurs, BACKUP fits as
much data as it can on the first volume, then dismounts it. Depending on
whether you specified more than one drive in the BACKUP command line or if
you are using a tape loader, BACKUP then performs the following actions:
• If you specified only one drive in the BACKUP command line and you are not
using a tape loader or operator assistance, BACKUP prompts you to remove
the tape that is in the drive and insert another one:
%BACKUP-I-RESUME, resuming operation on volume 2
%BACKUP-I-READYWRITE, mount volume DAILY02 on MUA0: for writing
Respond with YES when ready:
Note
If you are using OPCOM and the /ASSIST qualifier (the default), the
following message appears on your terminal:
%BACKUP-I-RESUME, resuming operation on volume 2
%MOUNT-I-OPRQST, Please mount volume DAILY02 in device MUA0:
BACKUP requests: Saveset DAILY.SAV, Volume number 02, write ENABLED
After you insert and load the second volume (or an operator fulfills the mount
request), BACKUP continues writing data to the second volume.
• If you specified multiple drives on the command line, BACKUP continues
writing data to the second volume, assuming the drive is loaded, is on line,
and has the correct volume label. BACKUP unloads the first volume and
displays the following message:
%BACKUP-I-RESUME, resuming operation on volume 2
• If you are using a tape loader, BACKUP continues writing data to the tape in
the next slot, assuming the tape loader has an adequate supply of correctly
labeled tapes. BACKUP rewinds and unloads the first tape and displays the
following message:
%BACKUP-I-RESUME, resuming operation on volume 2
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11.11.1 Multivolume Tape Labeling
In a multivolume save-set operation, BACKUP does not initialize the first volume
(unless you use the /REWIND qualifier). BACKUP does initialize subsequent
volumes. BACKUP determines the volume labels for subsequent volumes as
follows:
• If you did not specify a label on the command line, BACKUP uses the first six
characters of the save-set name to create a label for the first volume (unless
you use the /EXACT_ORDER qualifier, in which case BACKUP preserves
the volume label on the tape). For subsequent volumes, BACKUP uses the
first four characters from the label of the first volume plus the number of
the volume in the sequence. For example, suppose you are saving files that
require three tapes and the save-set name is BACKUP. If you do not specify
Using BACKUP 11–21