Hey,

A webserver i run goes down at least once a week. The day it goes down isn't fixed, it usually was a Friday but it went down today, Thursday.

I'm sure it's not a hardware issue because I've moved this property across 3 servers in the past 12 months and they all experience this crash.

Server Config:
Plesk 12
Nginx
PHP-FPM
Percona 5.6

Intel Xeon E5-2620
32GB DDR4 ECC RAM
2 x 2TB 7200RPM HDD's


how can I monitor the server applications for anomalies to somehow diagnose why the crash occurs?

You need to monitor the system - try http://collectl.sourceforge.net/ which combines the capability of several std tools.

Have looked closely at the logs - exactly what sort of crash?
Off the top of my head, it sounds like either a memory leak or a runaway process filling the disk or swap space (anything in the logs about oom-killer ?)

That's what I think is happening as well. I've tried looking at /var/log/messages but it doesn't report anything regarding the crash. Normal operation and then a void until the server reboots.

I don't have kvm access to the server so I don't even know where the server stands when it crashes.

The server crashes every week, the day sometimes varies and this usually occurs in off-peak hours. So traffic doesn't seem to be the trigger. Someone on the Odin forums pointed out that this may be because of Plesk's cron job, but I can't make heads or tails of how to identify which one it is.

You need to look at all the logs, not just the messages file.

You could just start with the basics - record the load avgs, mem usage and disk usage fairly frequently and either write to disk or email to yourself or scp to another system. (or some combination of thereof).

What sort of setup is it - real HW or a VM? Is it hosted somewhere or by a company you work for? Is it just a server at home?

Check you server logs and download zabbix - http://www.zabbix.com/ for monitoring your server.