dovecot - May 2010 - corrupted transaction log errors causing users mail to disappear temporarily

So Ive been looking into some problems with users reporting their mail 
goes missing for a second but then re-apears very soon after. I have 
tracked it down to happening at the same time these appear in the logs. 
Seems the transaction logs is getting corrupted somehow and then 
rebuilding itself (which works fine). The problem is while its re-builing 
the users think all of their mail is gone.

May  3 09:35:52 mailmachine dovecot: IMAP(test at domain.com): Corrupted 
transaction log file usershomedir/Maildir/dovecot.index.log seq 3: Invalid
transaction log
size (32708 vs 32840): usershomedir/Maildir/dovecot.index.log
(sync_offset=32708)

We are using load balanced servers and data/index's are stored in their 
home dir's over nfs. All my config details and nfs options are below. We 
are currently balancing based on source address so most of the time users 
imap/pop processes should stick to one machine as much as possible.

Does anyone know of a way to rid of this problem, or at least make it so 
dovecot just returns a server error to the imap/pop client instead of 
showing them a blank index?


#nfs options
defaults,intr,vers=3,bg,rsize=8192,wsize=8192,proto=udp	0 0



# 1.2.11: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.29.2-xenon-mail-ipv6-grsec x86_64 Debian 5.0.1
log_timestamp: %Y-%m-%d %H:%M:%S
protocols: imap pop3
listen(default): *:143
listen(imap): *:143
listen(pop3): *:110
disable_plaintext_auth: no
login_dir: /usr/var/run/dovecot/login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
login_user: dhmail
login_process_per_connection: no
login_processes_count: 150
login_max_processes_count: 1000
login_max_connections: 3000
max_mail_processes: 2500
mail_max_userip_connections: 7
first_valid_uid: 100
mail_privileged_group: mail
mail_location: maildir:~/Maildir
mmap_disable: yes
mail_nfs_index: yes
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
pop3_uidl_format(default): %08Xu%08Xv
pop3_uidl_format(imap): %08Xu%08Xv
pop3_uidl_format(pop3): UID%u-%v



-- 
Jordan Tardif
DreamHost

On Mon, 2010-05-03 at 10:41 -0700, Jordan Tardif wrote:
> May  3 09:35:52 mailmachine dovecot: IMAP(test at domain.com): Corrupted 
> transaction log file usershomedir/Maildir/dovecot.index.log seq 3: Invalid
transaction log
> size (32708 vs 32840): usershomedir/Maildir/dovecot.index.log
(sync_offset=32708)
..
> Does anyone know of a way to rid of this problem, or at least make it so 
> dovecot just returns a server error to the imap/pop client instead of 
> showing them a blank index?
This should return an error. Maybe the clients get confused by that?
> We are using load balanced servers and data/index's are stored in their
> home dir's over nfs. All my config details and nfs options are below.
We
> are currently balancing based on source address so most of the time users 
> imap/pop processes should stick to one machine as much as possible.
That's probably the cause. Some users use multiple clients from
different IPs. http://dovecot.org/list/dovecot/2010-May/049031.html
should help in future.