After mounting a tape, BACKUP processes information stored
in the volume header record of the tape before writing to it. Specifically,
BACKUP performs the following actions:
Checks the volume protection information
to ensure that you have the right to access the volume in the manner
you requested.
Checks the tape expiration date to prevent you from
initializing a magnetic tape that has not yet expired.
Compares the volume label specified in the BACKUP
command line (either explicitly with the /LABEL qualifier or implicitly
through the save-set name) to the volume label of the tape to prevent
you from creating a save set on the wrong magnetic tape. BACKUP
uses the following guidelines when processing tape labels:
If you specify a label that is longer
than six characters, BACKUP truncates the label to six characters.
If the volume label is less than six characters
long, BACKUP pads the volume label with the blank character to six
characters.
The first four characters of the volume label either
must match the first four characters of the label specified in the
BACKUP command line exactly, or must end with one or more underscore
characters. If the first four characters of the volume label end
with one or more underscore characters, and the label specified
in the command line matches the part of the volume label that appears
before the underscore characters, BACKUP accepts the match. (For
example, the volume label ABN_ matches the command line label ABN
but does not match the command line label ABNE.)
If the fifth and sixth characters of the volume
label are numbers between 0 and 9, BACKUP does not compare these
characters with corresponding characters in the label specified
in the BACKUP command line. Otherwise, the fifth and sixth characters
in the volume label must exactly match the corresponding characters
in the label specified in the BACKUP command line.
If the labels match, you have the proper protection, and the
tape is expired, BACKUP performs the designated operation.
If you specify more than one label with the /LABEL qualifier
and you do not specify the /EXACT_ORDER qualifier, the BACKUP operation
succeeds if any of the labels you specify match the tape's volume
label. For example, if the tape's volume label is MA1686, the BACKUP
operation will succeed if you specify the following list of labels
with the /LABEL qualifier:
/LABEL=(MA1684,MA1685,MA1686)
If the volume labels do not match, BACKUP displays the following
error message:
%MOUNT-I-MOUNTED, DKA0 mounted on _SODAK$MUA0:
%BACKUP-W-MOUNTERR, volume 1 on _SODAK$MUA0 was not mounted because
its label does not match the one requested
%BACKUP-W-EXLABEER, volume label processing failed because
volume MB1684 is out of order, Volume label MA1684 was expected
specify option (QUIT, NEW tape, OVERWRITE tape, USE loaded tape)
BACKUP>
Depending on the option you specify, you can quit the backup
operation (QUIT), dismount the old tape and mount a new one (NEW),
overwrite the data on the tape (OVERWRITE), or USE the loaded tape.
If you specify more than one label with the /LABEL qualifier
and you also specify the /EXACT_ORDER qualifier, BACKUP compares
the label of the loaded tape with the first label that you specified
with the /LABEL qualifier. If the labels match, BACKUP begins the
operation. If the labels do not match, BACKUP prompts you with the
previous message.
Assuming the volume labels of the tapes you use match the
corresponding labels on the command line, BACKUP continues processing
until it completes the operation or runs out of volume labels. If
you do not specify enough labels on the command line to complete
the operation or if the tape loaded does not have an ANSI label,
BACKUP prompts you to enter a label for the tape in the drive.
If
you use blank tapes or tapes that you intend to overwrite, use the
/IGNORE=LABEL_PROCESSING qualifier. This suppresses the previous
BACKUP message, which normally occurs if BACKUP encounters a non-ANSI-labeled
tape during a save operation.
For more information about the /EXACT_ORDER, /IGNORE, and
/LABEL qualifiers, refer to the HP OpenVMS System Management Utilities Reference Manual
.
HP OpenVMS System Manager's Manual, Volume 1:... 
Using BACKUP
