Resource Manager supports multiple hubs. A hub represents an instance of the zenhub daemon, through which all collector daemons communicate with the object and event databases. Hubs are now associated with a resource pool which helps with better collector distribution.
All collectors must belong to exactly one hub; however, a hub can have many collectors associated with it. All hubs (and indirectly all collectors) refer to the same object and event databases. Typically, only very large systems with more than five collectors (or more than 1,500 devices) benefit from multiple hubs.
The ZooKeeper service on the HBase cluster now maintains configuration data and provide distributed synchronization and group services.