Depending on the system model, both controllers can be in a single chassis, or one controller can be in one chassis and the other controller can be in a separate chassis.
To distinguish between the two nodes in an HA pair, one node is sometimes called the local node and the other node is sometimes called the partner node or remote node.
A dataset node refers to any of the nodes configured for a dataset.
A backup node refers to either a secondary or tertiary node that is the destination of a backup or mirror operation.
A disaster recovery node refers to the dataset node that is the destination of a failover operation.