FreeBSD 10 & default_vsz_limit causing reboots?

[Rick Romero]

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 at 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 = </etc/ssl/mail.pem
ssl_key = </etc/ssl/mail.key
ssl_key_password = na
userdb {
  driver = prefetch
}
verbose_proctitle = yes
protocol imap {
  imap_client_workarounds = delay-newmail tb-extra-mailbox-sep
  mail_max_userip_connections = 100
  mail_plugins = " quota zlib stats imap_zlib quota imap_quota"
}
protocol pop3 {
  mail_max_userip_connections = 100
  mail_plugins = quota
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
  pop3_uidl_format = %08Xu%08Xv
}