cluster with two nodes of ejabberd. can't run independently

I'm a bit new to the subject of ejabberd but following the manual to configure and start the managed 2 nodes in cluster to serve a domain. Everything works fine, except that:

* When I start only one node and the other is off, start the ejabberd erlang but never starts.

By typing the command ejabberdctl shows me the following message:

My questions would be:
How can I make the nodes can function without having run the 2 servers?
Why the server is waiting for the other node mnesia this asset?
What do you recommend for the administration and implementation of jabber service to fault tolerance for a domain?

I hope that if one server fails the other can be used independently.

Thanks for your help