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CHAPTER 11 Backup and Data Recovery
409
When you back up the files and restore them with the
CATALOG ONLY option,
you don’t see anything telling you that these files were links; in fact, this
information is not saved.
Adaptive Server IQ saves these files as though they were actually present in the
directory where the symbolic links reside. When you do the restore, the files
are recreated in the directories or on the raw partitions named by the database
name. Whether or not the links exist at restore time, they will never be used
again. The database is restored to its original location.
Unattended backup
With the ATTENDED OFF option, you can specify that no operator will be
present during a backup. Adaptive Server IQ currently supports two unattended
backup features:
• The operator does not need to respond to prompts during the backup.
• The archive devices can be stacker drives, which automatically load a set
of tapes into a single drive. You can use stacker drives for both attended
and unattended backups.
Unattended backup tries to detect all possible reasons for a backup failing
except tape media failure, and report any potential errors before attempting the
backup, such as available space on disk or tape, and consistent size and block
factor.
For unattended backup to disk, Adaptive Server IQ first tests whether there is
enough free disk space for the backup, However, it does not preallocate the
backup files to reserve the space. If another user writes to that disk and as a
result there is not enough room for the backup, the backup fails when disk
space runs out.
For backup to tape, you must estimate how much data each tape will hold, and
specify that number of kilobytes in the
TO
archive_device
parameter of the
BACKUP command. The backup program checks information stored internally
to see how much room it needs to back up your database. If it determines that
there is enough room on the tape, the backup proceeds. However, if you
overestimate the amount of space available on the tape(s) and the backup runs
out of space, the backup fails at that point.
If you omit the
SIZE parameter for an unattended backup, the entire backup
must fit on one tape.