On 23.3.2012, at 19.43, list@airstreamcomm.net list@airstreamcomm.net wrote:
Have you tried stress testing it with imaptest? Run in parallel for both servers: I did stress test it, but we have developed a "mail bot net" tool for the purpose. I should mention this was tested using dovecot 1.2, as this is our current production version (hopefully will be upgrading soon). Its comprised of a control server that starts a bot network of client machines that creates pop/imap connections (smtp as well) on our test cluster of dovecot (and postfix) servers. In my test I distributed the load across a two node dovecot (/postfix) cluster back ended by glusterfs, which has SAN storage attached to it. I actually didn't change my configuration from when I had a test NFS server connected to the test servers (mmap disabled, fcntl locking, etc), because glusterfs was an afterthought when we were stress testing our new netapp system using NFS. We have everything in VMware, including the glusterfs servers. Using five bot servers and connecting 7 times a second from each server (35 connections per second) for both pop and imap (70 total connections per second) split between two dovecot servers I was not seeing any big issues. The load average was low, and there were no errors to speak of in dovecot (or postfix). I was mounting the storage with the glusterfs native client, not using NFS (which I have not tested). I would like to do a more thorough test of glusterfs using Dovecot 2.0 on some dedicated hardware and see how much further I can push the system.
What did the bots do? Add messages and delete messages as fast as they could? I guess that's mostly enough to see if things work. imaptest anyway hammers the server as fast as it can with all kinds of commands.