Inconsistent expunge performance

Ken Murchison ken at
Wed Aug 18 19:42:51 EDT 2004

Nels Lindquist wrote:

> Hi there.
> Since upgrading to Cyrus IMAP 2.2.x, I've noticed some fairly extreme 
> performance degradation when it comes to expunging deleted mail.

Which 2.2.x version?

> 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.

Sounds like the folder may be corrupt, you are deleting a *lot* of 
messages, or you may be running 2.2.4-2.2.7.

> 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? 

None.  The only files involved in an expunge are cyrus.index, 
cyrus.cache, the message files, and the quota file (which in 2.2.4+ uses 
the cyrusdb interface).

 >  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 
> faster).
> 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:
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Kenneth Murchison     Oceana Matrix Ltd.
Software Engineer     21 Princeton Place
716-662-8973 x26      Orchard Park, NY 14127
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