How many agents are required for cluster data backup and recovery?

For successful data backup and recovery of a cluster Agent for Exchange has to be installed on each node of the Exchange cluster.

What happens with backup if the Agent for Exchange is not installed on all nodes?

If the Agent for Exchange is not installed on all cluster nodes (for example, the agent was manually uninstalled from one of the cluster nodes):

• The backup task completes with a warning, if the data selected for backup is hosted on the node with the Agent for Exchange installed.
• The backup task fails with error, if the data selected for backup is hosted on the node without the Agent for Exchange installed.