fence_ack_manual fails with "can't open /tmp/fence_manual.fifo: No such file or directory" when overriding fencing on Red Hat Enterprise Linux 5

Environment

• Red Hat Enterprise Linux (RHEL); including

  • Red Hat Enterprise Linux Server 5 (with the High Availability or Resilient Storage Add Ons)

• Red Hat High Availability Cluster with 2 or more nodes

  • It is likely this issue will apply to stretch clusters, but it is not compulsory

• All supported fence agents are affected (except fence_manual, which has different behavior)

  • Fencing is failing for some reason (for example, stretch cluster intersite link has failed) and manual intervention with fence_ack_manual is required to recover the cluster.
  • fence_ack_manual is not executed with the -e option for (-e)mergency fencing override:

  # fence_ack_manual -n primarynode.redhat.com