We recently switched over mail servers to one running dovecot and postfix on RedHat Enterprise 6. The mail store is NFS on a NetApp filer, the index files are on local disk. We have about 6000 total active users, though not all of them access the system at the same time.
All goes well for a while, then we start seeing errors like this in the log:
dovecot: imap-login: Error: net_connect_unix(imap) failed: Resource temporarily unavailable imap-login: Internal login failure (auth failed, 1 attempts)
And at this point, users can't log in. I don't know what Resource dovecot is running out of.
The machine is a 12-core Xeon 2.27Ghz, with 24GB RAM.
I have removed the 1024 nproc limit in /etc/security/limits.d/90-nproc.conf, and upped the nproc and nofile limits to 16384 and 65535 respectively, both in limits.conf, as well as adding ulimit statements in /etc/init.d/dovecot (belt and suspenders).
I have tried adjusting dovecot.conf, but I'm obviously missing something.
dovecot -n follows:
# 2.0.beta6 (3156315704ef): /etc/dovecot/dovecot.conf # OS: Linux 2.6.32-71.14.1.el6.x86_64 x86_64 Red Hat Enterprise Linux Server release 6.0 (Santiago) auth_master_user_separator = * auth_mechanisms = plain login default_client_limit = 5000 default_process_limit = 5000 disable_plaintext_auth = no mail_fsync = always mail_gid = 501 mail_location = maildir:~/Maildir:INDEX=/var/indexes/%n mail_nfs_storage = yes mail_plugins = quota mail_uid = 501 passdb { args = /etc/dovecot/passwd.masterusers driver = passwd-file master = yes pass = yes } passdb { args = /etc/dovecot/dovecot-ldap.conf driver = ldap } plugin { quota = maildir:User quota quota_rule = *:storage=200M } service auth { client_limit = 32768 unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } user = root } service imap-login { process_min_avail = 12 service_count = 0 } service pop3-login { service_count = 0 } shutdown_clients = no ssl_cert = </etc/pki/postfix/certs/nexus.pem ssl_key = </etc/pki/postfix/private/nexus_key.pem userdb { args = /etc/dovecot/dovecot-ldap.conf driver = ldap } protocol imap { mail_plugins = $mail_plugins imap_quota }
Thanks, -Kurt Hockenbury