Red Hat Knowledgebase

Netdump, Diskdump (in Red Hat Enterprise Linux 3/4), and Kdump (in Red Hat Enterprise Linux 5) are three different kernel crash dump facilities that are shipped with Red Hat Enterprise Linux.

After configuring one of these three kernel crash dump facilities, run the following commands to test if it works.

# echo 1 > /proc/sys/kernel/sysrq
# echo c > /proc/sysrq-trigger

Make sure that the above two commands are run in console (press ctrl+alt+F1), so that what’s happening when the system crashes can be seen. This will need to be performed to generate a vmcore.

With Netdump, it will be located at /var/crash/ip_of_the_server/.

In Diskdump, the vmcore will be recreated in the directory /var/crash/ with the name 127.0.0.1-date.

In remote Kdump(scp or nfs), the vmcore will be saved in the location Server:/location/host-date/, and the vmcore will be saved is /var/crash/date/.