CJ Kucera <exim@???> wrote:
> I'm curious if anyone's had any experience running a maildir system
> over NFS on a fairly large, fairly busy server. By "large" I
> mean a good 40 or 50 gigs or so, and by "busy" I mean well over
> a half a million messages per day. Basically, I just want to know
> if NFS is feasable for something like that, or if someone's tried
> that and watched their systems melt into goo.
In opposite to what some people say, Maildir + NFS is not that much
of a performance desaster. I've had good experiences with a much
larger setup running Exim + CourierIMAP (both with Maildir quotas
enabled which causes additional overhead). Load was balanced over
several machines, and Maildir on NFS was used as shared mail-storage.
Sure, Maildir/NFS causes a noticable performance impact right from
the start, but flexibility and scalability is great. Much better than
with most other solutions. Load increases because of spam and virus?
Simply buy new machines and add them to the existing ones.
Obviously, performance of the NFS server is critical here.
NFS version 3 is a must. And the NFS server should be very
good at caching data, because Maildir is locking-free and as
such you cannot cache much data on that level. So, applications
have to access Maildir directories and Maildir files quite often.
Although professional NFS storage (like EMC² or NetApp) should
be preferred (both offer affordable entry-solutions), you could
also build your own NFS storage. In the past, some operating systems
were said to give better NFS performance than others, but I don't
know if there's a big difference nowadays.
Logfiles, Exim's hint databases and the and mail queue should stay
on local disks.
Don't know if this is what you expected, but the bottom line is:
Yes, Exim with Maildir over NFS works. And it works really good. ;-)
Greetings, Andreas
