[OpenAFS] Backup methods

Todd M. Lewis Todd_Lewis@unc.edu
Fri, 30 Mar 2007 08:24:04 -0400

>> On Thu, Mar 29, 2007 at 10:07:42AM +0200, Gert Burger wrote:
>>> We are currently switching to openafs but are concerned about how to 
>>> backup our data.
> My problem with dumping a volume and doing a backup of that is that it 
> seems difficult to do incrementals.
> We only have enough space for about 3x the amount of data we on our 
> backup server and we dont use tapes at all. Therefore we need to 
> optimize our disk space usage so that we can keep daily incrementals for 
> up to a month(We do a full backup monthly).
> Currently I am considering just to backup the files and lose the ACL's, 
> seeing as we wont have complicated ACLs in anycase.

Okay, consider it, but also consider that the big wins that AFS/OpenAFS 
gives you come from volume management and ACLs, both of which will be 
lost in your backups if you only backup files. I appreciate your dilemma 

If you're going to end up scripting things, why not take the extra step 
when you backup a directory to create a file in each directory, say 
".__vol_acl_info" maybe, that contains the volume name, the path from 
the root of the volume to this directory, the owner of the root of the 
volume, the directory's owner and mode, and a dump of the directory's 
ACLs. This should give you enough information to restore a volume from 
your file-based incremental backups. Because these files would rarely 
change,  they should have minimal impact on your backup store. Plus, 
sometimes what you really need to restore isn't the files but the ACLs 
themselves, and this would let you do that.

It might be a bit of work, but it's probably worth it.
   / Todd_Lewis@unc.edu  919-445-9302  http://www.unc.edu/~utoddl /
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