Configuring the Behavior of Fenced Nodes With Kdump
If the hearbeat mechanism detects that a node with a mounted OCFS2 volume has lost contact with the other cluster nodes, that node is removed from the cluster in a process called fencing. Fencing prevents other nodes from hanging while trying to access resources that are held by the fenced node. By default, a fenced node automatically restarts so that it can rejoin the cluster as soon as possible.
However, under some circumstances, you might not want this default behavior. For example,
if a node often restarts for no obvious reason, then causing the node to panic instead of
restarting is preferable, so that you can troubleshoot the issue. By enabling Kdump on the
node, you can obtain a vmcore
crash dump from the fenced node and analyze
it to diagnose the cause of frequent node restarts.
To restore the default behavior, change the value of fence_method
back to reset
.
echo "reset" | sudo tee /sys/kernel/config/cluster/cluster-name/fence_method
Then, remove the panic
line from /etc/rc.local
if the line exists in the file.