[Dovecot] Significant performance problems

[Luben Karavelov]

On Wed, 06 Oct 2010 21:42:57 -0700, Chris Hobbs
<chobbs at nhusd.k12.ca.us> wrote:
> For documentation's sake, here's what I've done so far:
> 
> I do have one more idea I'll throw out there. Everything I've got
> here is virtual. I only have the one Dovecot/Postfix server running
> now, and the impression I get from you all is that that should be
> adequate for my load. What would the collective opinion be of simply
> removing the NFS server altogether and mounting the virtual disk
> holding my messages directly to the dovecot server? I give up the
> ability to have a failover dovecot/postfix server, which was my
> motivation for using NFS in the first place, but a usable system
> probably trumps a redundant one.
> 
> Chris
> 

I have done some tests here that shows that NFS is a major overhead 
compared to local filesystem on iSCSI volume. I have tested only 
NFS4 with linux clients and server. Finally we went with a couple 
of mails servers that mount OCFS2 shared volume - this setup also 
has some drawbacks in terms of complexity. 

You also could achieve redundant mail system with local fs (XFS for 
example) over iSCSI volume - one server will be standby and will
mount the volume and bring up a floating IP if primary goes down. 
You could automate such a setup with heartbeat/pacemaker or other 
cluster manager. Though, in such a setup you could not load-balance 
if you are serving only one mail-domain.

Best regards

-- 
Luben Karavelov
Research and development
Spectrum Net JSC

36, D-r G. M. Dimitrov Blvd.
1797 Sofia
Mobile: +359 884332840
url: www.spnet.net