How do I install and configure KDUMP if server hungs

If you have hanging server but no useful errors are shown in /var/log/messages, the way to find the reason is to install and configure KDUMP, so it will create a core dump file when server hungs. In some cases KDUMP could not help on XEN PV machines, however in any case you should try, on regular servers is really doing a good job.

Here are steps to install and configure KDUMP:

  1. Install kexec-tools:

    Edit /etc/kdump.conf, and set path variable to point to a directory with enough space to hold kernel dump file (default location is /var/crash/). File size will be about size of the server RAM + 1GB
  2. Edit /etc/grub.conf.

    For CloudLinux 5 add to the kernel line as another boot parameter:


    For CloudLinux 6 add to the kernel line as another boot parameter:


    For CloudLinux 7 edit /etc/default/grub and add crashkernel=160M to GRUB_CMDLINE_LINUX parameter so it looks like:

    GRUB_CMDLINE_LINUX=”crashkernel=160M rhgb quiet”

    Then regenerate grub.conf with the following command:


  3. For CLoudLinux 5 and 6 – add kdump to chkconfig and turn it On during boot:

  4. Modify /etc/sysctl.conf file and add following block to catch all possible panic states:

  5. Reboot.

 

After server boot check if kdump is running with:

 

Obtaining coredump if server hungs is described here .

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