As of late our four node dovecot 1.2.13 cluster has been experiencing a massive number of these dotlock errors:
Created dotlock file's timestamp is different than current time (1295480202 vs 1295479784): /mail/user/Maildir/dovecot-uidlist
These dotlock errors correspond with very high load averages, and eventually we have to turn off all but one server to stop them from occurring. We first assumed this trend was related to the NFS storage, but we could not find a networking issue or NFS related problem to speak of. We run the mail storage on NFS which is hosted on a Centos 5.5 host, and mounted with the following options:
udp,nodev,noexec,nosuid.
Secondly we thought the issues were due to NTP as the time stamps vary so widely, so we rebuilt our NTP servers and found closer stratum 1 source clocks to synchronize to hoping it would alleviate the problem but the dotlock errors returned after about 12 hours. We have fcntl locking set in our configuration file, but it is our understanding from look at the source code that this file is locked with dotlock.
Any help troubleshooting is appreciated.
Thanks,
Michael
# 1.2.13: /etc/dovecot.conf # OS: Linux 2.6.18-194.8.1.el5 x86_64 CentOS release 5.5 (Final) protocols: imap pop3 listen(default): *:143 listen(imap): *:143 listen(pop3): *:110 shutdown_clients: no login_dir: /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_process_per_connection: no login_process_size: 128 login_processes_count: 4 login_max_processes_count: 256 login_max_connections: 386 first_valid_uid: 300 mail_location: maildir:~/Maildir mmap_disable: yes dotlock_use_excl: no mail_nfs_storage: 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/lib64/dovecot/imap mail_plugin_dir(imap): /usr/lib64/dovecot/imap mail_plugin_dir(pop3): /usr/lib64/dovecot/pop3 auth default: username_format: %Ln worker_max_count: 50 passdb: driver: pam userdb: driver: passwd