[Dovecot] Significant performance problems

[Chris Hobbs]

  For documentation's sake, here's what I've done so far:

1) Implemented Timo's fixes to my config file (fixed shared INDEX, 
adjusted nfs settings for reality of only one server hitting it)

2) installed imapproxy on the webmail server at the recommendation of 
the developers of that product (SOGo)

3) Modified my NFS mount with noatime to reduce i/o hits there. Need to 
figure out what Brad's suggestions about readahead on the server mean.

4) Threw gobs of RAM at both the dovecot server (went from 4GB to 8) and 
the NFS server (from 1GB to 8). Also cranked up vCPUs on each to 4.

I hope that's enough to get things working much better tomorrow morning. 
I'll be back to report or beg for more. I really appreciate the quick 
responses and helpful advice.

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

On 10/6/10 4:32 PM, Chris Hobbs wrote:
>  Hi all,
>
> I'm sure my issues are a result of misconfiguration, but I'm hoping 
> someone can point me in the right direction. I'm getting pressure to 
> move us back to GroupWise, which I desperately want to avoid :-/

-- 
Chris Hobbs
Director, Technology
New Haven Unified School District

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