[OpenAFS] backup suggestions

[Mitch Collinsworth]

On Fri, 23 Jan 2004, Jason C. Wells wrote:

> A volume would almost always be modified, and therefore almost always
> backed up.

'vos dump -time' provides a means of performing incremental backups
of volumes.  Using this, just because a volume is modified doesn't
mean you have to dump the whole thing every time.


> Volumes are bigger than files and present certain
> difficulties.  Consistency of a large volume under heavy use while being
> backed up by amanda is something I would look closely at.

A non-issue.  AFS solved this problem ages ago with the backup volume
feature.  Typically you run 'vos backupsys' once a day to create a
cloned backup volume and then run your backups against the backup
volume, which is quiescent.  The backupsys mechanism takes care of
volume consistency issues, even under heavy load.


> I haven't configured AFS backup (butc) yet.  I do have an amanda
> installation.  I intend to use it in this manner to back up AFS files as
> soon as the FreeBSD AFS client is ready for prime time.  I may find out
> that my assumptions are incorrect in the future, but that's the plan as of
> right now.

We thought about doing it that way but wanted to get rid of butc and
the whole AFS backup system.  We wrote a glue layer to interface getween
AFS and amanda.  On the AFS side it uses 'vos dump -time' to get the
data.  On the amanda side it uses the gnutar dumptype to initiate dumps.
We then redirect amanda's path to gnutar to a wrapper script we wrote
that acts like gnutar to amanda, but invokes vos dump to get the data.
We also built a volume set mechanism to allow dumping collections of
volumes as a unit.  This is modeled after the similar feature in AFS
backup.

(The wrapper script actually looks at what it's being asked to dump,
invokes gnutar if it's not in AFS, and invokes our tools when it is.
This way we don't completely remove the gnutar functionality, in case
you want to dump both AFS and non-AFS filesystems in the same amanda
configuration.)

-Mitch