Automatic failover of a software-defined storage controller to handle input-output operations to and from an assigned namespace on a non-volatile memory device

An orchestration controller in a storage solution may establish namespaces, assign each namespace to a host, and establish software-defined storage controllers to handle input-output operations between the hosts and the namespaces. Each namespace is assigned to a given host and the input-output operations to and from the namespace are handled by a specific primary software-defined storage controller. In response to failure of the software defined controller, a secondary software-defined storage controller will take over handling of the input-output operations to and from the namespace. Also, in response to the failure of the software-defined storage controller, the host will direct subsequent input-output operations destined for the namespace to the secondary software-defined storage controller.