A memory module device for accessing memory, the memory module device comprising: a rank of active non-volatile memory devices (112, 202); a spare non-volatile memory device (114, 204) associated with the rank of active non-volatile memory devices; at least one volatile memory device; and a memory controller communicatively coupled to (i) the rank of active non-volatile memory devices via corresponding data bus lines of a data bus and (ii) the spare non-volatile memory device and the volatile memory device by a same set of data bus lines of the data bus which are distinct from the corresponding data bus lines of the data bus, and wherein the memory controller is configured to: set an assignable identification value of each of the active non-volatile memory devices of the rank of active non-volatile memory devices to a common value, wherein a non-volatile memory device responds to a memory access command if a corresponding selection identification value matches the assignable identification value; set an assignable identification value of the spare non-volatile memory device to a unique value different from the common value; receive a memory read request from a host; read, via the data bus, the rank of active non-volatile memory devices in response to the memory read request, wherein to read the rank of active non-volatile memory devices comprises to set a selection identification value of each of the active non-volatile memory devices and the spare non-volatile memory device associated with the rank of active non-volatile memory devices to the common value; and access, via the set of data bus lines, the volatile memory device contemporaneously with the read of the rank of active non-volatile memory devices. a rank of active non-volatile memory devices (112, 202); a spare non-volatile memory device (114, 204) associated with the rank of active non-volatile memory devices; at least one volatile memory device; and a memory controller communicatively coupled to (i) the rank of active non-volatile memory devices via corresponding data bus lines of a data bus and (ii) the spare non-volatile memory device and the volatile memory device by a same set of data bus lines of the data bus which are distinct from the corresponding data bus lines of the data bus, and wherein the memory controller is configured to: set an assignable identification value of each of the active non-volatile memory devices of the rank of active non-volatile memory devices to a common value, wherein a non-volatile memory device responds to a memory access command if a corresponding selection identification value matches the assignable identification value; set an assignable identification value of the spare non-volatile memory device to a unique value different from the common value; receive a memory read request from a host; read, via the data bus, the rank of active non-volatile memory devices in response to the memory read request, wherein to read the rank of active non-volatile memory devices comprises to set a selection identification value of each of the active non-volatile memory devices and the spare non-volatile memory device associated with the rank of active non-volatile memory devices to the common value; and access, via the set of data bus lines, the volatile memory device contemporaneously with the read of the rank of active non-volatile memory devices. set an assignable identification value of each of the active non-volatile memory devices of the rank of active non-volatile memory devices to a common value, wherein a non-volatile memory device responds to a memory access command if a corresponding selection identification value matches the assignable identification value; set an assignable identification value of the spare non-volatile memory device to a unique value different from the common value; receive a memory read request from a host; read, via the data bus, the rank of active non-volatile memory devices in response to the memory read request, wherein to read the rank of active non-volatile memory devices comprises to set a selection identification value of each of the active non-volatile memory devices and the spare non-volatile memory device associated with the rank of active non-volatile memory devices to the common value; and access, via the set of data bus lines, the volatile memory device contemporaneously with the read of the rank of active non-volatile memory devices.