A high availability (HA) failover manager maintains data availability of one or more input/output (I/O) resources in a cluster by ensuring that each I/O resource is available (e.g., mounted) on a hosting node of the cluster and that each I/O resource may be available on one or more partner nodes of the cluster if a node (i.e., a local node) were to fail. The HA failover manager (HA manager) processes inputs from various sources of the cluster to determine whether failover is enabled for a local node and each partner node in an HA group, and for triggering failover of the I/O resources to the partner node as necessary. For each I/O resource, the HA manager may track state information including (i) a state of the I/O resource (e.g., mounted or un-mounted); (ii) the partner node(s) ability to service the I/O resource; and (iii) whether a non-volatile log recording I/O requests is synchronized to the partner node(s). The HA manager interacts with various layers of a storage I/O stack to mount and un-mount the I/O resources on one or more nodes of the cluster through the use of well-defined interfaces, e.g., application programming interfaces.