[Dovecot] dovecot performance slow + time issue solved

[Paul A]

This is is follow up to my previous post about dovecot performance being
slow.

BTW, thanks to all that replied.

For one month we have been trying to figure why suddenly dovecot was slow.
We had two server's running dovecot with the same config and one was fine
while the other wasn't very slow. The server that was slow was on a virtual
server and we noticed some time errors in the logs and installed ntpd which
didn't help the problem.

After trying to tweak the config etc... I put dovecot on a new  server and
its running great. 

Before I was seeing 35% idle cpu with 700 + pop3 login sessions and another
400 imap. Since we moved to a new server, that has no time issues, we are
seeing 97% idle cpu with 50 - 70 pop3 logins and 40 imap while performance
is a lot faster. 

The previous system, giving us all the problems, was on a virtual server
running Virtual Iron software. The hardware was the same on both.

Here's what I was seeing, that contributed to the problems causing 7000
angry customers to call us :)

[root at pop etc]# ps aux | grep pop3 | wc -l
740
[root at pop etc]# ps aux | grep imap | wc -l
450
[root at pop etc]#


May 29 11:42:19 pop dovecot: POP3(xxx): Time just moved backwards by 1
seconds. I'll sleep now until we're back in present.
May 29 11:42:19 pop dovecot: POP3(xxx): Time just moved backwards by 1
seconds. I'll sleep now until we're back in present.
May 29 11:42:31 pop dovecot: POP3(xxx): Time just moved backwards by 1
seconds. I'll sleep now until we're back in present.
May 29 11:42:42 pop dovecot: POP3(xxx): Time just moved backwards by 1
seconds. I'll sleep now until we're back in present.

I was also getting postfix "backwards time" errors. I guess these errors
were causing login sessions to stay up longer then they should have which
backed up my server. I hope this helps someone out sooner as I had a feeling
the time was causing the problems but mgt here didn't let me try to move it
to another server until they exhausted all other options. 



Thanks,

Paul