10.13. Debug Logging for Distributed Lock Manager (DLM) Needs to be Enabled

There are two debug options for the Distributed Lock Manager (DLM) that you can enable, if necessary: DLM kernel debugging, and POSIX lock debugging.
To enable DLM debugging, edit the /etc/cluster/cluster.conf file to add configuration options to the dlm tag. The log_debug option enables DLM kernel debugging messages, and the plock_debug option enables POSIX lock debugging messages.
The following example section of a /etc/cluster/cluster.conf file shows the dlm tag that enables both DLM debug options:

<cluster config_version="42" name="cluster1">
  ...
  <dlm log_debug="1" plock_debug="1"/>
  ...
</cluster>
After editing the /etc/cluster/cluster.conf file, run the cman_tool version -r command to propagate the configuration to the rest of the cluster nodes.