About once or twice a week, ftpd shuts down on our new web hosting server. We spread the word to make sure no one at the office was doing it intentionally but it still happened.
The settings in "Webmin->Servers->ProFTPD Server" said it printUbuntu 12.04.5 LTSs logs to "/var/log/proftpd/proftpd.log".
The following 2 entries appear at random intervals about every 1-5 days:
2016-02-22 06:39:44,961 [server name] proftpd [server name]: ProFTPD killed (signal 15) 2016-02-22 06:39:44,962 [server name] proftpd [server name]: ProFTPD 1.3.5rc3 standalone mode SHUTDOWN Ubuntu 14.04.4 LTS Since its time of day is pretty random (sometimes in the middle of the night), I'm assuming it isn't a cron job or as a side effect of high traffic.
The average server load ("top" command) fluctuates between 0 and 0.2. The memory usage is around 90% (3695404 used, 4048216 free), though this also seems to be the case for our second largest webserver (in terms of pages hosted) and the old server (which now only has 5 pages left on it) is still using 70% of its memory (all of our servers are set to 4Gb). The swap memory is < 1% used (we use vmware).
We don't have this problem on our other servers. The main difference is that this one is Ubuntu 14.04.4 LTS instead of Ubuntu 12.04.5 LTS.