Multiple servers and NFS

[Richard Hector]

Hi all,

For some reason, I didn't go to http://wiki2.dovecot.org/NFS until now, 
and I'm starting to get worried ...

The plan was to have multple servers (MXes) receiving mail, and 
delivering via LMTP to multiple backend dovecot servers (with amavis in 
front of dovecot; LMTP both sides). Then we'd have multiple servers for 
clients to use IMAP or POP3.

This is more or less how the system already works, except with Courier 
IMAP, and postfix on the backends, delivering to maildirs with procmail.

But with the recommendation to use the Director for both IMAP/POP3 and 
LMTP - that starts to sound like I need a whole bunch more servers to 
run Directors and proxies, and even then it might not be a good idea to 
have different servers running lmtp and imap/pop.

One possible mitigating point is that our 'load balancing' is DNS 
round-robin, so a given client will probably stick with a single 
imap/pop server anyway, but if the user has multiple clients 
(desktop/mobile etc) then they may still hit different servers.

Can someone clarify best practice for a setup needing multiple servers 
for load balancing and redundancy?

Is Courier already likely to have been suffering these problems?

Oh, the NFS server is a NetApp Filer, if that matters.

I'm using dovecot 2.2.9 from debian wheezy backports, in order to get 
the quota policy daemon support.

Thanks,
Richard