cyrus server and backup

Ian G Batten I.G.Batten at
Fri Apr 4 09:49:50 EST 2003

On Fri, 04 Apr 2003, Phil Chambers wrote:
> I am concerned that because Cyrus is a "black box" system which keeps track of its 
> own internal organisation we may have problems if we restore a disc from our 
> backups.  It will take hours to do a backup and the files within the Cyrus structure 
> will be changing as we do it.  Are there going to be problems with inconsistencies 
> between files?

There are two answers to this.  The first is that doing snapshot backups
should be possible on most plausible platforms, either by dropping a
mirror off (requires mirroring, of course) or using fssnap (Sun) or LVM
(Linux) to do a hot backup.

The second is that in practice you can recover a mailbox by spinning on
the files and then using reconstruct to rebuild the metadata.  The worst
you're going to do is break the unread flags and suchlike.

> There is a secondary, but important use of our current backup service, which is to 
> dig users out of a hole when they make mistakes:  Occasionally a user will 
> accidentally delete a message or even a whole folder and then come and ask if I can 
> recover it for them.

We do that all the time.  We pull the entire mailbox back, then grep for
what the punter wants.

> With our current backup system it is ussually very easy because I have no problem 
> identifying the relevant files to be recovered.  I seems to that it will be 
> impossible to recover deleted messages because I will not be able to identify the 
> files which I need.  If I can identify the files, presumably there is no way to get 
> them back into the Cyrus system?

If you can identify them by size or date, you just put them back into
the mailbox and reconstruct it.


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