Assigning Roles to Nodes for Best Performance

The architecture of MapR software allows virtually any service to run on any node, or nodes, to provide a high-availability, high-performance cluster. Below are some guidelines to help plan your cluster's service layout.

Don't Overload the ZooKeeper

High latency on a ZooKeeper node can lead to an increased incidence of ZooKeeper quorum failures. A ZooKeeper quorum failure occurs when the cluster finds too few copies of the ZooKeeper service running. If the ZooKeeper node is also running other services, competition for computing resources can lead to increased latency for that node. If your cluster experiences issues relating to ZooKeeper quorum failures, consider reducing or eliminating the number of other services running on the ZooKeeper node.

Separate High-Demand Services

The following are guidelines about which services to separate on large clusters:

  • ResourceManager on ZooKeeper nodes: Avoid running the ResourceManager service on nodes that are running the ZooKeeper service. On large clusters, the ResourceManager service can consume significant resources.