Inconsistent expunge performance
nlindq at maei.ca
Wed Aug 18 18:14:07 EDT 2004
Since upgrading to Cyrus IMAP 2.2.x, I've noticed some fairly extreme
performance degradation when it comes to expunging deleted mail.
This behaviour is inconsistent from folder to folder, but quite
consistent WRT an individual folder.
I haven't been able to find much of a pattern involving numbers of
messages, ages of folders, etc. Some folders complete an expunge
almost immediately, some take nearly five minutes while generating
quite a high load on the server.
Is there some explanation for this? I've gone through the Wiki
regarding DB backends and I seem to have everything set up according
to the recommendations. Which database is most directly impacted by
an "expunge" operation? Is there anything I can do to alleviate this
problem? I tried putting imap/proc on tmpfs as discussed in the
performance documentation, but it didn't make any difference for the
expunge behaviour (though it would seem opening a folder is slightly
The server isn't very heavily loaded; there are less than 200
mailboxes and usually less than 20 concurrent users. IO shouldn't be
a problem; the disk is 10,000 RPM SCSI.
Any advice would be greatly appreciated!
Nels Lindquist <*>
Information Systems Manager
Morningstar Air Express Inc.
Cyrus Home Page: http://asg.web.cmu.edu/cyrus
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