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The Thursday 2007-04-26 at 13:52 +0100, G.T.Smith wrote:
> Carlos E. R. wrote:
> > As to backup to DVD, there is "dar" and "kdar". Plus "par", that I still
> > haven't evaluated.
> kdar is the frontend to dar... after looking at it in more depth it
> became apparent that one would still have move the dar slices to an iso
> image and the iso image would then need to be burned.
Obviously. But I understand it can burn them in parallel to the backup
procedure continuing.
> A further
> complication is although kdar apparently offers a 4Gb slice size for DVD
> the dvdtools burning tools will only accept a max of 2Gb per file
> (slice).
Yes. I haven't looked at it for use with dar, but you know that you are
not limited to iso images for dvd burning: I myself use XFS, wich doesn't
have that limitation. I wonder I f I could use them from dar.
> (And not even that... setting slice size to 2Gb still caused
> problems).
At 2 GB, 400 MB are wasted. Better four slices of 1.1 GB.
> To get a listing from a dar rquires access to first and last
> slices, this would suggest the for an N slice backup one would need (N
> mod 2) + (N div 2) DVDSs for a two slice solution with first DVD
> containing slice 1 and slice N, kdar provides no mechanisms for such
> slice management across media. While a bulk restore would be ok do not
> think this would work to well for retrieving a single file (one would
> not only have to know which slice a file was in but which DVD, and
> heaven forbid if the file is split between two slices on two DVDs). dar
> has some other limitations as well which took it out of picture....
I still have to evaluate dar, but I should think it makes an index to
facilitate this. Any good backup solution should handle this.
I miss pctools backup from 198X-190X, for MsDos... it could backup to
floppies files way larger than a single floppy, and restore without
problems - even with media errors. My backups from that era still work.
> A brief look at par (which dar seems to link into) suggests this not
> suitable for my requirements...
No, par is a complement to protect against errors in media, so that files
are still recoverable. It is not a backup solution on itself.
> What I intend to look at is the possibility of using to rdiff-backup to
> build its structures and create a tar image of this structure (which
> probably be ok for disaster recovery but not brilliant for archive
> retrieval). Dirvish is impressive but I think it would best with a SAN
> or dedicated backend backup server solution.
Both rdiff-backup and Dirvish work on a similar principle, and backup to
disk. You can use Dirvish (or rdiff-backup) for day to day backup, then
backup to external media (tape, dvd, whatever) from the Dirvish made
backup, instead of from the original (they mention this procedure on their
faq).
> > And there are some other solutions in the distro, I think.
> >
> I have been looking... I dunno after years of being a sys-admin one of
> things that still seems to give the most grief is backup >:o
Of course.
- --
Cheers,
Carlos E. R.
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