Ok,
So this is really more of an observation than anything else.
I had a FreeBSD 10.1 server that was running great. Some SSL issue came up, or I upgrade Dovecot in ports - something occurred and the machine started rebooting randomly. It would run for 2 weeks, then reboot. It might run for 5 days and then reboot. So I started doing more FreeBSD upgrades, thinking it was a kernel issue. The reboots only increased.
This weekend I started thinking I might actually be having hardware issues. But, since I don't have easy physical access to the box and it's REALLY under loaded, I figured what the hell and upraded to 10.2 on Sunday. I think it rebooted 4 times after that on Sunday, and then another 2 times Monday morning.
Its worth noting that while I have crash dumps enabled, they don't seem to be occurring. So hardware is still a possibility.
After the 2nd Monday morning reboot, I started to wonder if there was some sort of process issue. Besides the OS upgrades - I had been monitoring the Dovecot logs for when the process limits are reached, and increasing them. It's a 'big' box, and load is typically between .30 and .50. CPUs aren't overtaxed, and most of the memory is dedicated to ZFS. The reboots are so short, I've only received one 'down' alert due to them. So it's a conerning issue, but not really impacting production.
On a whim I changed my default_vsz_limit (as I had been increasing every other limit but that) from 384M to 512M. The system hasn't rebooted in 24hours.
Now that could be a coincidence, but I thought I'd at least put it out there.
If you see anything weird in my dovecot config, let me know - My config was originally vpopmail, but over time I've migrated to SQL-only.
root@romulus:/usr/local/etc/dovecot # dovecot -n # 2.2.18: /usr/local/etc/dovecot/dovecot.conf # OS: FreeBSD 10.2-RELEASE amd64 auth_master_user_separator = * auth_mechanisms = plain login auth_username_translation = %@ auth_verbose = yes default_login_user = dovecot default_vsz_limit = 512 M disable_plaintext_auth = no first_valid_gid = 89 first_valid_uid = 89 last_valid_gid = 89 last_valid_uid = 89 log_path = /dev/stderr login_greeting = Ready. login_trusted_networks = 172.16.100.0/24 mail_fsync = never mail_plugins = " quota zlib stats" mail_privileged_group = mail namespace compat { alias_for = hidden = yes inbox = no list = no location = prefix = INBOX. separator = . } namespace inbox { inbox = yes location = prefix = separator = . } passdb { args = /usr/local/etc/dovecot/dovecot-master-sql.conf driver = sql master = yes pass = yes } passdb { args = /usr/local/etc/dovecot/dovecot-sql.conf driver = sql } plugin { quota = maildir quota_rule = Trash:storage=+10%% stats_refresh = 30 secs stats_track_cmds = yes } protocols = imap pop3 service anvil { client_limit = 3175 } service auth { client_limit = 3684 unix_listener auth-master { mode = 0600 } } service imap-login { process_limit = 1536 process_min_avail = 25 service_count = 1 } service imap-postlogin { executable = script-login rawlog /usr/local/etc/dovecot/lastauth-imap.sh user = vpopmail } service imap { executable = /usr/local/libexec/dovecot/imap imap-postlogin process_limit = 1536 } service pop-postlogin { executable = script-login /usr/local/etc/dovecot/lastauth-pop.sh user = vpopmail } service pop3-login { process_limit = 1536 process_min_avail = 15 service_count = 1 } service pop3 { executable = /usr/local/libexec/dovecot/pop3 pop-postlogin } service stats { fifo_listener stats-mail { mode = 0600 user = vpopmail } } shutdown_clients = no ssl_cert =