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I know, the question is kinda generic, but I really can't be more specific because I simply have no idea what's going on:

It has now happened twice (once on our live server and once on our test server), that the response becomes completely unresponsive. I can't reach our website in any browser and I can't connect via SSH, all I get is Connection closed by remote host. I have to do a hard reset using hetzner's web-tool to manage servers. That's the only way I can get the server to be reachable again. A soft reset (hetzner says is the equivalent of sending ctrl+alt+del) has no effect at all. After doing a hard reset I can SSH in again and the website is back up.

The server in question is an EX41-SSD from hetzner with Ubuntu 14.04.5. Our website runs using the LAMP stack, meaning Apache, MySQL and PHP.

The thing is, I have no real idea where to start looking for the source of this issue. I'm a web developer who's done some server admin stuff before, but nothing more than setting up machine, hardening them, setting up puppet. Never really had to investigate server outage and the likes.

The one thing I did find is a 3h gap in /var/log/syslog. There is some output from a cron of ours, then a whole lot of "^@^@^" and then the output caused by the hard reset or rather the boot process following it.

Any idea where else I might look? Or what I can do, to make investigations in the future easier? Are there some monitoring tools I should install/setup?

Thank you anyway!

David Behler
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    You should probably check with your hosting provider. – ewwhite Sep 18 '16 at 09:08
  • The block of null bytes (^@) in the log is caused by the hard reset and doesn't tell you anything about the actual problem. Apart from that I agree with @ewwhite. You should bring that up with your hosting provider. – Tilman Schmidt Sep 18 '16 at 09:57
  • You might look for another provider ;-) I had the same problem a few years ago with a dedicated server out of the EX4*-line. After searching for help I found out, that others had the same problem with the same product. I tried to write processes, cpu usage and other things every second - without any new information. Server freezed from one second to another. Support of Hetzner also could not help. – chrwhm Sep 18 '16 at 11:27
  • Will do that if this happens again. Can't say I'm looking forward to migrating to a new server/hoster... – David Behler Sep 29 '16 at 12:33

1 Answers1

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You should try last command

# last
Mr. Pundir
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  • That only shows me last logins, right? I'm the only one with access to the server and therefor all I'm seeing are logins by myself. Were you hinting at a possible hack? – David Behler Sep 29 '16 at 07:22
  • you should contact your hosting support.. failure in power backup is also a possible cause.. – Mr. Pundir Sep 29 '16 at 08:12