In a Hyper-V cluster, virtual machines may migrate between cluster nodes. Follow these recommendations to set up a correct backup of clustered Hyper-V machines:
A machine must be available for backup no matter what node it migrates to. To ensure that a backup plan can access a machine on any node, run the plan under a domain user account that has administrative privileges on each of the cluster nodes.
We recommend that you specify such an account for the agent service during the Agent for Hyper-V installation. Otherwise, you will need to specify credentials for such account in every centralized backup plan or recovery task.
Install Agent for Hyper-V on each node of the cluster.
Register all of the agents on the management server, either during installation or later.
Back up clustered machines by using the management server, rather than by connecting directly to a cluster node.