[Dovecot] constant mailbox rebuilding with dovecot 1.0.10

[Philip J. Hollenback]

On 02/26/08, Timo Sirainen wrote:
> On Tue, 2008-02-26 at 15:56 -0500, Philip J. Hollenback wrote:
> > I've recently upgraded to 1.0.10 in hopes that this problem would go
> > away but no luck.  I've got some users at my company with large
> > inboxes on maildir (say 22,000 messages).  Their mailboxes are hosted
> > on nfs and dovecot is configured to do dotlocking.
> 
> Are there multiple Dovecot servers accessing the mailboxes? Can the same
> user have different connections to different servers at the same time?
> 
> This sounds like NFS caching problems that are described in
> http://wiki.dovecot.org/NFS

The real problem seemed to be when users run multiple imap clients and
they stomp on each others' index files on the nfs filesystem.

I believe I have this fixed.  I should clarify that there is only
one dovecot server which in turn nfs-mounts the mailbox filesystem from
a netapp.  I realized after reading all the dovecot nfs documentation
that I could point the INDEX variable to a local filesystem on the
dovecot server.  I did that with the following dovecot.conf
default_mail_env:

default_mail_env = mbox:%h/mail:INBOX=/var/mail/%u:INDEX=/opt/dcache/%u

because the default at my company is mbox.  Then for each maildir user I
set a dovecot.passwd entry as follows:

user:XXXXX:501:100::/home/user:/bin/false::Maildir:/home/%u/Maildir:INDEX=/opt/dcache/%u

finally I set my dovecot.conf locking/nfs options as follows:

mmap_disable=yes
dotlock_use_excl = no
lock_method = fcntl
mbox_read_locks = dotlock
mbox_write_locks = dotlock

since I'm using dovecot 1.0 I believe this is the correct way to do
dotlocking on the mbox files and fcntl locking on the index files (which
remember are on the local filesystem under /opt/dcache).

Since I've made this change I've seen no more corrupted index files.

P.

-- 
Phil Hollenback
hollenba at schrodinger.com
Schrodinger, Inc.