[Dovecot] distributed mdbox

[list at airstreamcomm.net]

On Wed, 21 Mar 2012 09:56:12 -0600, James Devine <fxmulder at gmail.com>
wrote:
> Anyone know how to setup dovecot with mdbox so that it can be used
through
> shared storage from multiple hosts?  I've setup a gluster volume and am
> sharing it between 2 test clients.  I'm using postfix/dovecot LDA for
> delivery and I'm using postal to send mail between 40 users.  In doing
> this, I'm seeing these errors in the logs
> 
> Mar 21 09:36:29 test-gluster-client2 dovecot: lda(testuser34): Error:
Fixed
> index file /mnt/testuser34/mdbox/storage/dovecot.map.index:
messages_count
> 272 -> 271
> Mar 21 09:36:30 test-gluster-client2 dovecot: lda(testuser28): Error:
Log
> synchronization error at seq=4,offset=3768 for
> /mnt/testuser28/mdbox/storage/dovecot.map.index: Append with UID 516,
but
> next_uid = 517
> Mar 21 09:36:30 test-gluster-client2 dovecot: lda(testuser28): Error:
Log
> synchronization error at seq=4,offset=4220 for
> /mnt/testuser28/mdbox/storage/dovecot.map.index: Extension record update
> for invalid uid=517
> Mar 21 09:36:30 test-gluster-client2 dovecot: lda(testuser28): Error:
Log
> synchronization error at seq=4,offset=5088 for
> /mnt/testuser28/mdbox/storage/dovecot.map.index: Extension record update
> for invalid uid=517
> Mar 21 09:36:30 test-gluster-client2 dovecot: lda(testuser28): Warning:
> fscking index file /mnt/testuser28/mdbox/storage/dovecot.map.index
> Mar 21 09:36:30 test-gluster-client2 dovecot: lda(testuser34): Warning:
> fscking index file /mnt/testuser34/mdbox/storage/dovecot.map.index
> 
> 
> This is my dovecot config currently:
> 
> jdevine at test-gluster-client2:~> dovecot -n
> # 2.0.13: /etc/dovecot/dovecot.conf
> # OS: Linux 3.0.0-13-server x86_64 Ubuntu 11.10
> lock_method = dotlock
> mail_fsync = always
> mail_location = mdbox:~/mdbox
> mail_nfs_index = yes
> mail_nfs_storage = yes
> mmap_disable = yes
> passdb {
>   driver = pam
> }
> protocols = " imap"
> ssl_cert = </etc/ssl/certs/dovecot.pem
> ssl_key = </etc/ssl/private/dovecot.pem
> userdb {
>   driver = passwd
> }

I was able to get dovecot working across a gluster cluster a few weeks ago
and it worked just fine.  I would recommend using the native gluster mount
option (need to install gluster software on clients), and using distributed
replicated as your replication mechanism.  If you're running two gluster
servers you should have a replica count of two with distributed replicated.
You should test first to make sure you can create a file in both mounts
and see it from every mount point in the cluster, as well as interact with
it.  It's also very important to make sure your servers are running with
synchronized clocks from an NTP server.  Very bad things happen to a
(dovecot or gluster) cluster out of sync with NTP.