When ActiveMQ is used in a master-slave set-up with Fabric8, using the standard profiles, then both Zookeeper-based and filesystem-based master-slave coordination locking will be used. It seems that the recommendation is to use both of these if possible. However, there is a "standalone" mode where the broker will use filesystem-based locking in preference to ZK locking.

However, it should be possible to use only ZK locking, if the filesystem does not offer adequate locks. Conversations with the engineering teams in the past have suggested that this should be possible, but it's never been clear whether it has been tested, or is supportable.

Many customers are working in environments where they can't use one of the few, recommended shared filesystems (e.g.,NFSv4). These customers could, perhaps, use Fabric8 and ZK locking to make good the deficiencies in their filesystems. It would be good to have an official statement on whether this is something we support.