The HV_USE_ELM environment variable in hvenv is automatically initialized to enable or disable ELM according to the status of CF:
If CF is not installed, HV_USE_ELM is set to 0 and the default UDP heartbeat recovery timeout is 45 seconds.
If CF is installed, HV_USE_ELM is set to 1 and the default UDP heartbeat recovery timeout is 600 seconds.
You can override the default recovery timeout with 'hvcm -h'.
Point
If the heartbeat recovery timeout is too short, premature node kills may occur even though ELM is operational.
