dovecot - Dec 2007 - Stale NFS file handle and duplicated messages

We recently moved all our users from the Washington IMAP server to
Dovecot. There has been a substantial improvement in performance, but
some users are reporting duplicate messages, and we see 'Stale NFS file
handle' errors in the syslog. Does anyone know what would cause this ?
The errors relate to the index file, eg.

Nov 29 00:49:47 imap-e.ucl.ac.uk dovecot: [ID 107833 mail.error]
IMAP(ccaazzz): close() failed with index
 file /home/ccaazzz/imap-mail/.imap/mbox/dovecot.index: Stale NFS file
handle

Our IMAP servers (5 of them) are a mixture of Sparc Solaris 8 and
Solaris 10 machines, using NFS to a central mailspool running on
AIX. We are using a mixture of Dovecot 1.0.3 and 1.0.5.

dovecot -n gives:

# 1.0.3: /usr/local/etc/dovecot.conf
base_dir: /var/run/dovecot/
listen: *:143
ssl_listen: *:993
ssl_ca_file: /usr/local/ssl/certs/sureserveredu.pem
ssl_cert_file: /usr/local/ssl/certs/imap-server_ucl_ac_uk.crt
ssl_key_file: /usr/local/ssl/certs/imap.key
ssl_cipher_list: MEDIUM:!LOW
disable_plaintext_auth: no
login_dir: /var/run/dovecot//login
login_executable: /usr/local/libexec/dovecot/imap-login
login_user: pp
login_process_per_connection: no
login_processes_count: 30
max_mail_processes: 1500
first_valid_uid: 200
mail_location: mbox:%h/imap-mail:INBOX=/nfs/rcs/mail-spool/mail/%u
mmap_disable: yes
mbox_lock_timeout: 55
mbox_dotlock_change_timeout: 50
mail_drop_priv_before_exec: yes
mail_executable: /usr/local/sbin/dovecot-login.csh
mail_plugins: mbox_snarf
mail_plugin_dir: /usr/local/lib/dovecot
namespace:
  type: private
  separator: /
  inbox: yes
auth default:
  passdb:
    driver: pam
  passdb:
    driver: passwd
  userdb:
    driver: passwd
plugin:
  mbox_snarf: ~/imap-mail/mbox



--

Adrian Barker,
Internet Technology Section
Information Systems
University College London, Gower Street, London WC1E 6BT
External phone: +44 20 7679 5140,  Fax (+44) 20 7388 5406
Internal phone: x 25140
Email: A.Barker at ucl.ac.uk

On Sat, 2007-12-08 at 10:21 +0000, Adrian Barker wrote:
> 
> We recently moved all our users from the Washington IMAP server to
> Dovecot. There has been a substantial improvement in performance, but
> some users are reporting duplicate messages, and we see 'Stale NFS file
> handle' errors in the syslog. Does anyone know what would cause this ?
> The errors relate to the index file, eg.
> 
> Nov 29 00:49:47 imap-e.ucl.ac.uk dovecot: [ID 107833 mail.error]
> IMAP(ccaazzz): close() failed with index
>  file /home/ccaazzz/imap-mail/.imap/mbox/dovecot.index: Stale NFS file
> handle
> 
> Our IMAP servers (5 of them) are a mixture of Sparc Solaris 8 and
> Solaris 10 machines, using NFS to a central mailspool running on
> AIX. We are using a mixture of Dovecot 1.0.3 and 1.0.5.
Have you read http://wiki.dovecot.org/NFS? v1.0 still has some problems
with NFS if you try to access the mailboxes from multiple servers at the
same time. I've done a lot of work on v1.1 to get this working right.

I'd suggest either

a) Move index files to local disks

b) Try how v1.1 works with mail_nfs_*=yes settings. I'm going to make
the first v1.1 "release candidate" soon, maybe within a few days.
Beta10
still has one performance issue unfixed, so might not be a good idea to
use that yet. :)
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Timo Sirainen wrote:
> On Sat, 2007-12-08 at 10:21 +0000, Adrian Barker wrote:
>> We recently moved all our users from the Washington IMAP server to
>> Dovecot. There has been a substantial improvement in performance, but
>> some users are reporting duplicate messages, and we see 'Stale NFS
file
>> handle' errors in the syslog. Does anyone know what would cause
this ?
>> The errors relate to the index file, eg.
>>
>> Nov 29 00:49:47 imap-e.ucl.ac.uk dovecot: [ID 107833 mail.error]
>> IMAP(ccaazzz): close() failed with index
>>  file /home/ccaazzz/imap-mail/.imap/mbox/dovecot.index: Stale NFS file
>> handle
>>
>> Our IMAP servers (5 of them) are a mixture of Sparc Solaris 8 and
>> Solaris 10 machines, using NFS to a central mailspool running on
>> AIX. We are using a mixture of Dovecot 1.0.3 and 1.0.5.
> 
> Have you read http://wiki.dovecot.org/NFS? v1.0 still has some problems
> with NFS if you try to access the mailboxes from multiple servers at the
> same time. I've done a lot of work on v1.1 to get this working right.
> 
> I'd suggest either
> 
> a) Move index files to local disks
> 
> b) Try how v1.1 works with mail_nfs_*=yes settings. I'm going to make
> the first v1.1 "release candidate" soon, maybe within a few days.
Beta10
> still has one performance issue unfixed, so might not be a good idea to
> use that yet. :)

Thanks for replying. I have read the wiki page on using NFS. In general,
our users should only be accessing a single IMAP server at any one time
- we have a hardware load-balancer in front of the IMAP servers, but it
is possible that some have IMAP clients on multiple machines that are
left running. This can be checked from the logs. Would keeping the index
files locally on the IMAP servers have an impact on performance ? Before
moving to Dovecot, IMAP performance was a very fraught issue, and the
benefits of Dovecot have been substantial - the load on some of our file
servers is 1/4 of what it was before the change, so we are very grateful
for all the work that has gone into Dovecot. Unless the problem gets
worse, we can probably wait until 1.1 is released.


--

Adrian Barker,
Internet Technology Section
Information Systems
University College London, Gower Street, London WC1E 6BT
External phone: +44 20 7679 5140,  Fax (+44) 20 7388 5406
Internal phone: x 25140
Email: A.Barker at ucl.ac.uk