All VMware Aria Operations clusters consist of a primary node, an optional replica node for high availability or continously availability, and optional data nodes.

When you install VMware Aria Operations, you use a VMware Aria Operations vApp deployment to create role-less nodes. After the nodes are created and have their names and IP addresses, you use an administration interface to configure them according to their role.

You can create role-less nodes all at once or as needed. A common as-needed practice might be to add nodes to scale out VMware Aria Operations to monitor an environment as the environment extends larger.

The following node types make up the VMware Aria Operations analytics cluster:

Primary Node
The primary node is the initial, required node in VMware Aria Operations. All other nodes are managed by the primary node.

In a single-node installation, the primary node manages itself, has adapters installed on it, and performs all data collection and analysis.

Data Node
In larger deployments, additional data nodes have adapters installed and perform collection and analysis.

Larger deployments usually include adapters only on the data nodes so that primary and replica node resources can be dedicated to cluster management.

Replica Node
To use VMware Aria Operations high availability (HA) and continous availability (CA) the cluster requires that you convert a data node into a replica of the primary node.

The following node types are a member of the VMware Aria Operations cluster but not part of the analytics cluster:

Witness Node
To use VMware Aria Operations continuous availability (CA), the cluster requires that you have a witness node. Each VMware Aria Operations cluster can have only one witness node. If the network connection between the two fault domains is lost, the witness node acts as a decision maker regarding the availability of VMware Aria Operations.
Note: If you require an agent to collect data, you must deploy a cloud proxy. For more information on how to deploy a cloud proxy, see Installing Cloud Proxy.