[Dovecot] Dovecot and NFS with file locking

[Nate Sanders]

Greetings all,

I'm trying to get an understanding of a problem we are facing here.
We're currently running dovecot 1.0-beta3 and have a long standing issue
of system crashes on our mail server (Debian Linux 2.4.27-2-k7-smp).

Here's what is happening:

The machine hangs and the system load climbs as high as 80.0+. Yet, the
system response is not effected. Command line is still responds
instantly. There are multiple running dovecot PIDs, even if I stop the
service. If I try to kill or -9 the PIDs, they will not die. The machine
is DOA and must be forcefully restarted. Issuing a reboot will cause the
machine to hang when it attempts to unmount network shares.


Here's the setup:

- Dovecot 1.0-beta3
- lock_method = dotlock
- mmap_disable = yes

/var/mail is store locally on the mail server and access via NFS to ALL
remote machines. All remote machines have /var/mail sym linked to the
NFS share on Mail.

/home on Mail is NFS'd to another set of servers where IMAP mail folders
reside in mbox format. All client machines have /home sym linked to the
second NFS server.

In other words, there's a lot of NFS shares and one mail transaction can
involve 3 machines.


What I'm trying to find out is the current state of NFS locking with
Dovecot. This system hang happens 1-3 times a week. The current /home
NFS mounts are running from SGI machines on IRIX 6.5. Clients are all
Linux (debian) 2.4 or Linux (ubuntu) 2.6.

Is our setup too much for Dovecot to handle? Are there other variables
we're not looking at here?

Thanks everyone.

-- 
==============================================
Nate Sanders                  nate at ima.umn.edu
Associate Systems Manager     (612) 624 - 4353
           http://www.ima.umn.edu/
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Institute for Mathematics and its Applications
University of Minnesota
400 Lind Hall, 207 Church St. SE
Minneapolis, MN 55455-0463
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