Dedicated server Hetzner - how to find out the cause of the intermittent hang of the web server?

Question

Apache HTTP Server

There is a dedicated server from Hetzner (EX4S), on the server installed a lot of different sites (mainly on WordPress), before the server worked fine (it could freeze once a month, and sending a request to technical support was a manual reboot, since ctrl + alt + del and hardware reset did not help). At the moment, the server hangs up about every day, at about the same time (at night), and only a manual reboot through technical support also helps. There is a suspicion that competitors are making a certain attack on the server in order to hang it (mini DDOS or something similar, possibly using some kind of vulnerability). After a reboot, the server does not hang again (even if I managed to reboot within 10 minutes after the hang) and works fine for another day or more. That is, the attack / problem is one-time, but periodic.
I would have thought it was due to the high concurrent traffic, but the server has handled heavy loads before without problems (and the CPU/RAM load isn't that great after a reboot).
Question - what logs and where can I see to understand what caused the freeze? Technical support cannot answer, says that the server did not respond completely and it was impossible to see anything.
Server Details:
Installed Parallels Plesk Panel v11.5.30_build115130819.13
Debian 6.0.7
GenuineIntel, Intel(R)Core(TM) i7-3770 CPU @ 3.40GHz
32GB RAM
Apache
PHP Version 5.3.3-7+squeeze17
suhosin
Log files:
https://dl.dropboxusercontent.com/u/5349131/server...(800kb)

Answer 1

watch all the system logs
when it freezes ask Lara and see what's on the screen,
well, hire an admin already)))

Answer 2

Show /var/log/messages (well, /var/log/messages.1; zcat /var/log/messages.2.gz)
It also makes sense to look in /proc/mdstat if raids are synching.

Answer 3

/var/log/kern.log
/var/log/syslog

to get started in the studio

Answer 4

Added the requested log files (800kb):
https://dl.dropboxusercontent.com/u/5349131/server...
Please help me understand.

Answer 5

Are you sure it's stuck for sure? Have you ordered LARA?
We had a similar problem, and it was due to the curve of the network settings by the Hetznerites, about once a day the network fell on the server and got up only after a manual restart.
Supports excuse themselves from such problems, saying "did you try to live in the river for a week? wait until it falls?".
A good kick and a little swearing helped. They cleared the ARP and it's been a week now with no problems.

Answer 6

See what's hanging in your
cron cron -e
You say that it hangs at the same time - perhaps the backup process or log rotation hangs your server. View in the control panel for what time the backup is scheduled.
DOS? The request logs /var/log/nginx/access.log or /var/log/apache/access.log will help you determine it, depending on the web server you are using. If there are more than a dozen requests per second per IP, this is definitely dos.
Server completely unresponsive? Show /var/log/kern.log and /var/log/syslog, the reasons are described there.