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mills at cc.umanitoba.ca
Sat Sep 27 20:50:00 EDT 2008
On Sun, Sep 28, 2008 at 09:42:27AM +1000, Bron Gondwana wrote:
> On Sat, 27 Sep 2008 13:46:39 +1000, "Rob Mueller" <robm at fastmail.fm> said:
> > Some things to try if you haven't:
> 6. Don't fetch every single file from your cyrus server every backup run.
> One nice property of cyrus's on-disk format is that all the data files
> are immutable once created: b/user/brong/798. is always going to be the
> same file, no matter what happens to the mailbox. Only the cyrus.*
> files and new data file actually need to be fetched.
> (our system also stats the cyrus.* files, and uses some other funky tricks
> to ensure consistent backups with minimum IO)
Most of our restores are done from ZFS snapshots. We keep two weeks
of them. That's worked out extremely well. We use Networker with
tapes for longer-term backups. It's that that seems to cause the
Certainly our Networker backup system has no knowledge of the structure
and properties of the Cyrus IMAP spool. It would just read every file
for a full backup, or look at timestamps for an incremental backup.
I don't know if much can be changed in the way it operates. However,
we may be able to change the way it takes backups if contention is
really the problem. I'm not convinced that it is just now.
-Gary Mills- -Unix Support- -U of M Academic Computing and Networking-
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