Apache ZooKeeper is a centralized service for maintaining configuration information across a RadiantOne cluster. Although RadiantOne comes bundled with ZooKeeper to simplify installation in Dev/QA environments, it is discouraged to use this architecture in production. Shutting down a redundant RadiantOne server will also shut down ZooKeeper on this server. Because a ZooKeeper ensemble must have a quorum of more than half its servers running at any given time, this can be a problem for cluster integrity and stability. The solution is to deploy ZooKeeper in a separate, external ensemble.

Other advantages of having a ZooKeeper ensemble separate from the RadiantOne nodes include:

  • As a general best practice, you should only have one main service per server. This allows machines resources to be devoted to a single service and not have to compete for resources with other services.
  • You can choose the number of ZooKeeper nodes to deploy to meet your HA requirements (e.g. 3, which allows for the failure of 1 server, or 5 which allows for the failure of 2 servers) independently from the number of RadiantOne nodes you need to serve client requests.
  • You can choose the number of RadiantOne nodes to meet your needs. Only one node needs to be up for the service to work. A RadiantOne cluster of 2 nodes might be sufficient whereas if ZooKeeper was on the same server as RadiantOne you would be required to have 3 nodes to accommodate the requirements of the ZooKeeper ensemble for HA.
  • This de-coupled (single service per server) architecture is better for running in container technologies like Docker, simplifying deployment.
  • Easier to troubleshoot problems and there is one less point of failure per machine.

For details on installing RadiantOne in a Dev/QA environment see These Installation Steps.

For details on installing RadiantOne in a production environment, setup the External ZooKeeper Ensemble. Then, refer to RadiantOne Installation on how to point to an external ZooKeeper ensemble.

The installers are available at: Create an account to login. Once logged in, navigate to: /Installers/<RadiantOne_MainVersion>/<RadiantOne_PatchVersion>/rli-zookeeper-external<version> file applicable for your operating system>