Hi all, we are experencing some, may be strange, slowness in our dovecot/postfix mail system. We have three dovecot 2.0.1 server with LMTP, POP3 and IMAP enabled. Three shared OCFS2 filesystem are used for mail storage. We have too a load balancer based on dovecot director in front of these three server. Our SMTP cluster receives mail and send by LMTP to load balancer.

Everything work flowless, but sometime, under heavy load, three server slow down a lot. Our mail gateway logs a lot of: status=deferred (host 10.194.1.20[10.194.1.20] said: 451 4.4.0 Remote server not answering (DATA output timeout)

IP 10.194.1.20 is dovecot director.

Looking at mbox servers log nothing seem to happen, but stracing lmtp process we can see stat system calls to all Maildir files, as if dovecot was recalculating quota and regenerating maildirsize file.

It happens always when LMTP tries to deliver a mail to an overquota account.

Is this possible and right? How can we look deeper in system to have more information?

Best regards

Luca

PS: dovecot configuration for maildir servers is:

# 2.0.1: /etc/dovecot/dovecot.conf # OS: Linux 2.6.26-2-686-bigmem i686 Debian 5.0.5 auth_master_user_separator = * auth_verbose = yes disable_plaintext_auth = no mail_location = maildir:~/Maildir mail_plugins = $mail_plugins notify mail_log quota managesieve_notify_capability = mailto managesieve_sieve_capability = comparator-i;octet comparator-i;ascii-casemap fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date spamtest spamtestplus virustest passdb { args = /etc/dovecot/dovecot-sql.conf.ext driver = sql } plugin { mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename mail_log_fields = uid box msgid from size quota = maildir:User quota quota_warning = storage=95%% quota-warning.sh 95 %u quota_warning2 = storage=80%% quota-warning.sh 80 %u sieve = ~/.dovecot.sieve sieve_dir = ~/sieve sieve_global_dir = /etc/dovecot/sieve/global/ sieve_global_path = /etc/dovecot/sieve/default.sieve } protocols = imap pop3 lmtp sieve service auth { unix_listener auth-userdb { group = dovecot mode = 0600 user = dovecot } } service director { inet_listener { port = 8100 } } service lmtp { inet_listener lmtp { address = 10.194.1.31 127.0.0.1 ::1 port = 24 } } service managesieve-login { inet_listener sieve { address = 10.194.1.31 127.0.0.1 ::1 port = 4190 } process_min_avail = 0 service_count = 1 } service quota-warning { executable = script /virtual/shared/quota-warning.sh unix_listener quota-warning { user = vmail } user = dovecot } ssl_cert = </etc/ssl/certs/dovecot.pem ssl_key = </etc/ssl/private/dovecot.pem userdb { args = /etc/dovecot/dovecot-sql.conf.ext driver = sql } verbose_proctitle = yes protocol lmtp { mail_plugins = $mail_plugins quota sieve } protocol lda { mail_plugins = $mail_plugins quota } protocol imap { mail_plugins = $mail_plugins quota imap_quota } protocol pop3 { mail_plugins = $mail_plugins quota }