[Gllug] Tape backups

[t.clarke]

Martin's definition of a backup would seem to be pretty comprehensive,
but I would have to disagree that it has to let you see what changed since
when.  That surely depends on whether you are doing incremental backups or
complete ones?

For a quick restore of a completely buggared file-system a complete backup
of the filesystem at a very recent point in time would seem a good approach,
plus if appropriate a separate backup of any changes since that time.
Backup strategy must be geared to one's own specific usage patterns and
requirements.
I would heartily agree that backups need to be secure, in a data-grade firesafe,
offsite, on non-fragile media,  so that if the proverbial s**t hits the fan the
data can be recovered reliably to promptly.

Our approach, on a relatively modest database, is to copy twice daily the whole
unmounted filesystem  (raw dd) to another disc partition, remount and carry on,
and then backup the disc copy to tape.  This keeps downtime to a matter of
seconds.  The tape-copies are re-read against the disc and compared to ensure
that the tape has been written OK.  On the few occasions when I have need of
some historic info the tapes have always been readable.
As the database is quite small, we also whizz the copy overnight to another box
with a DVD writer and write an ISO file as well.



Tim
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