[Dovecot] distributed mdbox

[list at airstreamcomm.net]

On Fri, 23 Mar 2012 16:06:25 +0200, Timo Sirainen <tss at iki.fi> wrote:
> On 23.3.2012, at 15.39, <list at airstreamcomm.net>
<list at airstreamcomm.net>
> wrote:
> 
>> I was able to get dovecot working across a gluster cluster a few weeks
>> ago
>> and it worked just fine.  I would recommend using the native gluster
>> mount
>> option (need to install gluster software on clients), and using
>> distributed
>> replicated as your replication mechanism.
> 
> Have you tried stress testing it with imaptest? Run in parallel for both
> servers:
> 
> imaptest host=gluster1 user=testuser pass=testpass
> imaptest host=gluster2 user=testuser pass=testpass
> 
> http://imapwiki.org/ImapTest
> 
> And see if Dovecot logs any errors.

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.