This morning MySQL crashed on my server, and after further investigation, it looks like systemd reloaded which caused MySQL to go down. I found these lines in the syslog at the moment everything went down:
May 5 06:34:15 s1 systemd[1]: Reloading.
May 5 06:34:15 s1 systemd[1]: Starting Message of the Day...
May 5 06:34:15 s1 systemd[1]: Starting Daily apt download activities...
May 5 06:34:15 s1 systemd[1]: Started Message of the Day.
May 5 06:34:15 s1 systemd[1]: Stopping MySQL Community Server...
Would I be correct in saying that systemd going down is what caused MySQL to crash? Is there explanation for why systemd reloaded -- no one with access to the server ran daemon-reload, nor does that line appear in "history".
Additionally, we have munin installed, and there does not appear do have been any cpu or memory issues at that time, although the disk may have had high i/o, although that might have been caused by mysql restarting and not the other way around.
Are there any logs or directions I can look as to why systemd and mysql restarted?