[Dovecot] Migration questions...

[Timo Sirainen]

On May 14, 2009, at 8:19 PM, Phillip Macey wrote:

> On 15/05/2009 9:49 AM, Timo Sirainen wrote:
>> On Fri, 2009-05-15 at 09:35 +1000, Phillip Macey wrote:
>>
>>> We are having some performancec issues on our server at the moment  
>>> - all I can put it down to is the large size of some maildirs. Eg.  
>>> `ls -ld Maildir/cur` might show a directory >20Mb in size for some  
>>> of our users (20-30k emails).
>>> (Performance issues == everything is running ok then all of a  
>>> sudden load avg goes through the roof, system cpu time goes crazy.  
>>> Reading mail grinds to a halt. Then everything recovers just as  
>>> suddenly and the load avg gradually returns to normal levels)
>>>
>>
>> Do you have POP3 users? What clients do your users typically use?
>>
> 50% pop. 50% imap.. Roughly.

With POP3 users those kinds of I/O bursts can happen when a lot of  
messages don't have their virtual size known. See Maildir performance  
in http://wiki.dovecot.org/POP3Server