STONITH is a vital component of the configuration of a Linux-HA system. We highly recommend it.
Two things are necessary to enable STONITH in Linux-HA:
set stonith-enabled to true in the <crm_config> section in your CIB
Configure STONITH resources in the <resources> section of your CIB
For more information on the role of STONITH in an HA system see: Split-brain, Quorum and fencing article