Hot backups

[Craig Ringer]

> I've been using XFS on LVM and I think it doesn't have the problem you
> describe. With XFS, you have to call 'xfs_freeze -f' before taking the
> snapshot, then you 'xfs_freeze -u' it again.

That's exactly what I need for reiserfs :-( . Darn. I guess that's 
something to note in the Cyrus FAQ - xfs makes backing up Cyrus easier.

> Would be nice to have something like a 'cyrus_freeze' command. Maybe there
> is a way to do this with SIGSTOP/SIGCONT?

I was thinking about that, but came to the conclusion that it wouldn't 
save me from things like half-completed db writes, etc. I couldn't 
SIGSTOP the master (to prevent new LMTP deliveries) without also 
preventing new IMAP connections :-(

Craig Ringer