When you configure HDP HA solution using RHEL, your Hadoop cluster comprises the following two components:
RHEL HA cluster
Overall Hadoop cluster
![[Important]](../common/images/admon/important.png) | Important |
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The RHEL HA cluster is a subset of the overall Hadoop cluster. |
Typically, the overall Hadoop cluster must include the following types of machines:
The RHEL HA cluster machines. These machines must host only those master services that require HA (in this case, the NameNode).
Master machines that run other master services such as JobTracker, HBase master, etc.
Slave machines that run slave daemons like Datanodes, TaskTracker, RegionServers etc.
Client machines.
A network that connects all the machines.
The following illustrates the topology of a sample Hadoop cluster when configured for HDP HA using RHEL:
