[CentOS] How to determine why a server is not responding

[Alexander Dalloz]

Am 11.04.2013 17:36, schrieb nan del bosc:
> Hi to all!
> 
> We're using CentOS 5.5 64bits for our Plesk 11.

That's insane! Why on earth do you run a 2,5 years old unpatched public
system? You are asking for trouble and innocent third will be the
victims of your hacked system.

> This week we had the following problem 3 times...
> 
> Suddenly, the server stops responding in all services (SSH, Apache,
> Postfix, ...) but ping works!
> 
> After wait a few minutes (or 2 hours some times) the server continues
> unresponsive until we reboot. After reboot we search on /var/log/messages
> but cannot find useful information...
> 
> Apr 11 14:56:05 s1 postfix/smtpd[8263]: SQL engine 'intentionally disabled'
> not supported
> Apr 11 14:56:05 s1 postfix/smtpd[8263]: auxpropfunc error no mechanism
> available
> Apr 11 14:56:42 s1 postfix/smtpd[8370]: SQL engine 'intentionally disabled'
> not supported
> Apr 11 14:56:42 s1 postfix/smtpd[8370]: auxpropfunc error no mechanism
> available
> Apr 11 14:56:47 s1 postfix/smtpd[8391]: SQL engine 'intentionally disabled'
> not supported
> Apr 11 14:56:47 s1 postfix/smtpd[8391]: auxpropfunc error no mechanism
> available
> Apr 11 14:56:47 s1 postfix/smtpd[8392]: SQL engine 'intentionally disabled'
> not supported
> Apr 11 14:56:47 s1 postfix/smtpd[8392]: auxpropfunc error no mechanism
> available
> Apr 11 16:55:42 s1 syslogd 1.4.1: restart.
> Apr 11 16:55:42 s1 kernel: klogd 1.4.1, log source = /proc/kmsg started.
> Apr 11 16:55:42 s1 kernel: Bootdata ok (command line is ro root=/dev/xvda1
> console=xvc0 console=hvc0 xencons=hvc)
> Apr 11 16:55:42 s1 kernel: Linux version 2.6.18-194.26.1.el5xen (
> mockbuild at builder10.centos.org) (gcc version 4.1.2 20080704 (Red Hat
> 4.1.2-48)) #1 SMP Tue Nov 9 13:35:30 EST 2010

That's a Xen Domain. So IPMI, as suggested by others, will not work.

> Apr 11 16:55:42 s1 kernel: BIOS-provided physical RAM map:
> Apr 11 16:55:42 s1 kernel:  Xen: 0000000000000000 - 0000000080000000
> (usable)
> Apr 11 16:55:42 s1 kernel: No mptable found.
> Apr 11 16:55:42 s1 kernel: Built 1 zonelists.  Total pages: 524288
> Apr 11 16:55:42 s1 kernel: Kernel command line: ro root=/dev/xvda1
> console=xvc0 console=hvc0 xencons=hvc

[ ... ]

> What can we do? what can we test?

First, update your system to the latest 5.9 + updates!

Talk to your hoster. If your Xen VM has issues other guests on the same
hardware may have too. Or another VM on the hosts consumes so much
resources that your VM does not respond any longer.

[ ... ]

> Thank's!
> 
> --
> ---
> Salut!

Alexander