Backing up to DVDs
Bob Edwards
Robert.Edwards at anu.edu.au
Mon Nov 11 14:39:45 EST 2002
Antti.Roppola at brs.gov.au wrote:
> We recently were quoted around that for an internal DVD-R
> (Pioneer A05).
>
> Bob's CD backup script would be pretty easy to change to
> support DVD. Since it's all tarr'ed up, you'd get your
> permissions being saved too. No terribly difficult to browse.
>
> Antti
Someone just pointed out to me that the "Bob" referred to in this message was
probably me, but I didn't write the CD backup scripts - they came from Drake
Dierdrich, as far as I can recall.
Our backup system uses "rsync" (excellent code from Tridge and co.) which we
customised, the customisation having been rolled back into rsync some years
ago, namely the --backup-dir option.
We backup to a live disk on a remote server (in another building on campus),
export that back (read-only) back to our staff desktops using NFS and use the
--backup-dir option to create "reverse incrementals" of all files modified or
deleted each (week) day. The archive directory of reverse incrementals are
also exported back to staff desktops, as well as being tar'd and compressed
and scp'd back to our CD-ROM burning machine for regular (weekly) archival
onto CD-ROM (we also leave live versions on the backup server for about 2
months or so, depending upon available disk space).
One recent enhancement to this scheme (implemented by Steven Hanley) is to
detect all archived files that are proper sub-files of their respective
current version (ie. all files that have been appended to, such as e-mail
folders and log files) and to remove the old version from the archive. This
reduces the size of the archive each day by about 40%.
Our system has been running reliably for about 3 years. The main advantages are:
- cheaper than tape drives and tapes
- offsite always (no need to manually move or even handle tapes)
- almost no operator intervention required
This last point is important as any staff member can recover any (daily)
version of a file changed or deleted over the past 2 months or so from their
desktop without operator intervention. After 2 months, files need to be
recovered from the CD-ROMs, requiring mounting, uncompressing and untarring
etc. the archives. Still generally easier than searching a tape.
Cheers,
Bob Edwards.
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