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I have a CentOS 6.5 server for hosting. It has sshd, httpd, mysqld, smtpd, dovecot, postfix, named working fine. but since last year I updated the server to PHP 5.4, MySQL 5.5, it starts having problems. Sometimes all services do not work except it response to ping. I added some monitoring service from 3rd party website. That website told me that my server reply 200 to httpd so it does not alarm me. All I can do is ask people in Data center to reboot it.

I want to know where is the problem. Since I cannot even use SSH to connect to server, I don't know what is the problem. Is there any way or script to find out where is the problem?

  • Does your hosting provider offer out-of-band management? (Remote console?) If not, all you can do is ask they reboot. – Aaron Copley Mar 23 '15 at 15:51
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The first step would be looking at all log files, in particular /var/log/syslog.

Without any information my guess would be that it is an out-of-memory condition. Any service (including ssh) would stop, ping is pretty much the only service still working because it is directly handled by the kernel.

  • I don't have syslog in the log folder. I only have boot.log, dmesg, maillog, mcelog, messages, secure, and some other files. which one should I look into? If it is the out-of-memory problem, how can I find which service used all the RAM? – hatted Mar 24 '15 at 1:43
  • I found the Mem used very fast. Mem: 24685044k total, 23025540k used, 1659504k free, 516436k buffers Swap: 10223608k total, 152k used, 10223456k free, 17774752k cached – hatted Mar 24 '15 at 2:09
  • but free shows i used only 4G ram.# free -m total used free shared buffers cached Mem: 24106 22523 1582 0 505 17411 -/+ buffers/cache: 4607 19498 Swap: 9983 0 9983 – hatted Mar 24 '15 at 2:13

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