It will work, however if the connection between live and backup is not reliable you may get a split brain problem.
So, it's ok as long as the connection is reliable.
We are looking into adding Zoo Keeper through newer versions on activemq-artmis (next generation). We haven't been able to do the proper announcements yet but hornetq was donated to apache-activemq, and we are moving the dev there. think about this as hornetq-3 but doing it as part of activemq, and think about activemq doing their next version with us.
I would suggest the documentation is updated with this piece of information, because I have been discussing this with others that are having the same interpretation, and it's a shame if they disregard HornetQ because of this.
Congrats on the alliance between hornetq and activemq!
Just to be clear, the phrase, "If it can connect to more than half the servers, it will become active," gives you the impression that a live/backup pair using replication requires 3 servers?
Yes I read it takes 3 or more nodes to work with replication. With 2 nodes it's not able to connect to more of than half the backup servers, and since it's the only one left it can't know if this is a split brain and it bail out.
That's the reason I was asking because it didn't make sense to me, it sounded like it was a requirement to use 3 or more servers to use the replication strategy, unless you choose the shared-store case instead.