[Dovecot] Multi Server Exim/Dovecot and NFS

[Robert Blayzor]

On Jul 16, 2012, at 9:15 AM, Robert Schetterer wrote:
> There where hot disputs relating such setups, read list archive
> 
> i guess nfs is simply not the ideal solution, however its used in real
> existing setups, also maildir may not ideal
> 
> for good advice there should be more info about how many mailboxes , how
> much traffic, mailbox size , loadbalancing solution etc
> 
> dont think exim is critical envolved in this ( but i dont know exim very
> good )
> 
> however someone from the list with equal setup may share his experience
> with you
> 
> as far i remember, Timo posted good advice also ,for nfs setups in the past


We're talking about tens of thousands of mailboxes and at least half a dozen servers involved.  There is quite a bit of traffic.  We've been running Maildir via NFS with another mailserver product for some time, and it's been ok as far as the shared file system standpoint.

I don't know why Maildir would be "not ideal".  It seems to be the only option when it comes to NFS.

NFS is used extensively in our network and we already have a major investment with NetApp, and have been very happy with them.

The only issue I see right now is Dovecot index file write bashing if a user accesses their mailbox from multiple locations at the same time, and I gave that example in the previous post.  That seems to be more and more common these days but still not the norm for 80%+ of the mailboxes we have.

From the MTA side of things, it looks like having Exim write directly into the ~/Maildir/new/ is the only sane choice since mail can be coming into a mailbox from a number of servers at the same time.  We've used this extensively in the past with no issues.

We use a Brocade ADX to load balancing POP and IMAP sessions to the server.  Stickiness doesn't really buy you anything on POP3 since a session connects, does it's thin and disconnects.  IMAP on the other hand, I believe can have multiple connections open from the same client, so I think sticky would help.  But neither of those help when the client is connecting from a different IP address.


Robert Blayzor
INOC, LLC
rblayzor at inoc.net
http://www.inoc.net/~rblayzor/