Thiago Monaco Papageorgiou wrote:
We have 2 server running with the same load, one with our old pop3
solution (out of date) and other with Dovecot. We realized that dovecot
are comsuming more CPU, and this consumption is growing day by day. When
we starts dovecot, it runs between 40%-45% of CPU consumption and our
old solution runs on 30-35%. This is quite acceptable, so no problem
here. The problem is one day after it jumps to 45%-55% of cpu
comsunption while the old pop3 solution runs on the same CPU consumption
of one day before (30%-35). I attached a graph with this information.
Are your using leaving mail on the server? If not, you may find it
advantageous to disable the indexing, since it's of no real use for "drive
by collect" mail.
In this graph the green line is dovecot CPU consumption and the blue
line is the old solution.
In this graph we restart dovecot at monday morning. This restart is
noticed as a big fall of CPU consumption(green line) in the graph. After
that, it stay between 40%-45%, one day after it runs on 45%-55% and next
day, it reaches 50%-60%! You can notice that the blue line (old pop3
solution) runs with the same behavior, so we have the same load. We have
other monitoring informations that confirm it.
This, to me, is consistent with Dovecot spending a lot of time indexing the
overnight deliveries as everyone logs on in the morning.
Are you using dovecot deliver as your LDA?
Is there any dovecot problem or wrong configuration that could cause
this degeneration of CPU performance? Any sugestion about what can be
the cause of this?
It could be that Dovecot is doing work you don't need it to. By which I
mean building indices.
I attached dovecot -n output. Two important information: we store the
mailboxes in NFS and we are only using pop3 protocol.
As I said above, if your users are using this service ONLY to collect mail,
not to store it, then the indexes Dovecot tries to maintain are a waste of
effort.
You can read more about POP3 configuration in the wiki at:
http://wiki.dovecot.org/POP3Server
The MailLocation page also has some notes about index file placement, including:
"""
If you really want to, you can also disable the index files completely by
appending :INDEX=MEMORY.
"""
--
Curtis Maloney
cmalo...@cardgate.net
