Hi all,
Please correct me if I'm going about this the wrong way.
We currently have a 3 system Mail server set up - two machines are the load balanced frontends running Dovecot and Postfix, and the third machine is our NFS. Over the past 4 months or so, I've tweaked and optimized our mail servers, and we receive roughly 3 million emails a day combined through this setup.
Sometimes, the IO Wait is horrible on the load balanced servers - it can get up into the 80-90% range sometimes - it's usually when a lot of email is being passed, or there are a lot of POP3 and IMAP connections.
One item which I believe to be hurting I/O performance is the fact I used a RAID 10 setup using SATA II drives on an LSI Logic SATA I controller, in 32 bit mode. Until we rebuild our mail setup (which may be another year down the road), I want to make sure these servers are optimized to the fullest just in case we get heavy I/O usage, it doesn't slow down if at all possible.
One thing I noticed is that when issuing a 'ps aux | grep -i pop' or 'ps aux | grep -i imap' I see the same username 2,3,4,5 times, sometimes more. When issuing a 'tail -f /var/log/dovecot.log' I notice that some users log into POP3 every 3 seconds, sometimes sooner.
Without upsetting the customer, is there anything I can do on my end to disallow people logging into POP3 multiple times at once?
Any tips on this is very much appreciated. Thanks in advance.
Patrick