Re: [courier-users] NFS server load thru the roof

> > > We have much the same system setup and problems described here:
> > >
> > > http://thread.gmane.org/gmane.mail.i....general/21782
> > >
> > > Briefly, mail spool is mounted over NFS, everything runs smoothly
> until
> > > we
> > > turn IMAP on and server load goes off the scale (NFS client load 300,
> NFS
> > > server load 10, with server in wait about 80% of the time). There are
> no
> > > discernable errors in our logs, and everything still "works", albiet at
> a
> > > snail's pace.

<snip>

> > > Although it is curious that our MTA (postfix) does not incur any load
> hit
> > > at all, and we are delivering hundreds of mails an hour at least.
> Should
> > > Courier IMAP be that much more of a heavy hitter??
>
> How big are your users's mailspools?

almost 100G. Until last evening, we had 20K users in one flat directory. I
had read that that is not a problem in reiserfs, but just to be sure, we
hashed the whole user base out overnight, and today the problem remains,
so....

> the MTA is only going to be delivering one message at a time, but
> courier-imap is going want to check every file in the mailboxes the user
> is accessing to get the message headers.

Makes sense

> I had the same problem with Imap with the mail spool on AFS when the
> working
> set size of the users reading mail via imap exceeded the local AFS disk
> cache. It was solved by increasing the afs cache size. (I'm currently at
> around a 10GB AFS cache).

Er, I am not sure where/how to look at and adjust that kind of setting, but
would be very willing to try if you can provide any tips or links. I didn't
think that NFS dealt with disk logistics itself...

> What version of NFS are you using? I'm pretty sure that nfs is going to
> require a network round-trip for *every* message in the currently active
> imap folder, and it is likely not doing any local cacheing.

Latest and greatest v4. Huh, so what are you suggesting?

THANK YOU for responding!




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