I've seen this happen a couple of times as of late. Basically, I make a change to the ISPConfig settings and most services on the box are terminated immediately. Terminated services include Apache, Postfix, Amavis, Dovecot, syslogd... even SSHd seems to have restarted (my terminal session was disconnected, but I was able to reconnect immediately).
The specific nature of the change made in ISPConfig was SSL-related. I was installing an SSL certificate for a site... pretty routine. The only thing unusual was that the site in question was not "Enabled" at the time.
The only thing in Apache's error log is
[Fri Apr 27 06:50:03 2012] [notice] caught SIGTERM, shutting down
There is nothing at all in /var/log/mail.log, and logging stopped after this "crash" (syslogd tanked), so new events are not being registered either.
EDIT: I noticed that about 10 minutes before this incident, the following was logged:
Apr 27 06:37:26 localhost amavis: (04085-11) (!!)file(1) utility (/usr/bin/file) FAILED: run_command: can't fork: Cannot allocate memory at /usr/sbin/amavisd-new line 3077, line 4946.
Seems like the server's memory supply was exhausted. What else could cause this kind of across-the-board service termination? Maybe ISPConfig is just a red-herring in this case, and the change simply consumed enough memory to cause the crash.
Where else should I be looking for clues as to what, exactly, happened?
Also, is there any easy means by which to bring all services back online? Or should I just restart the box?
Thanks for any help!