Re: Distributed mailsystem

[Eugene Crosser <crosser@online.ru>]

We have >100,000 maiboxes here on an NFS server (with failover option),
Zmailer and UW imapd/ipop3d right now running on two separate machines,
but expected to become load-balanced on multiple machines RSN.

Problems: productivity of backend Ethernet that carries the NFS (non-
switched 100 Mbit started choking, now have Gig at the NFS server and
100 Mbit at clients), and physical access to the disk array.  Should
be real fast FC, or Ultra3, possibly multi-channel.  Or multiple
NFS servers.  Look at NAS appliances (NetApp, Auspex, EMC Celerra).
Don't forget to make hashed mailbox directory tree.

NFS shares need to be exported with "root" option and mounted with
"noac" option (at least so the documentation recommends).

With high traffic, scheduler spool becomes bottleneck, buy fast local
disks, or install more servers in the farm (thus lowering traffic on
each one).  200,000 messages per day is really enough for a single
machine.

"DLM" not used here (never heard of that), using old-style dotlocking.

Eugene