High Availability Planning

Configuring a cluster for HA (High Availability) involves running redundant instances of specific services, and configuring NFS properly. When properly licensed and configured for HA, the MapR cluster provides automatic failover for continuity throughout the stack.

The following table provides the minimum number of instances of each core service required for HA:

Service	Minimum # Instances	Comments
CLDB	2
ZooKeeper	3	At least 3 are needed to maintain a quorum in case one instance fails.
HBase Master	2
JobTracker	2
NFS	2	NFS can be configured for HA using virtual IP addresses (VIPs).
ResourceManager	2

In HA clusters, it is appropriate to run more than one instance of the WebServer with a load balancer to provide failover. NFS can be configured for HA using virtual IP addresses (VIPs).

The following sections provide information about HA planning: