A memory system is disclosed comprising a memory controller and a first set of volatile memory devices defining a first memory hierarchy. The first set of volatile memory devices are disposed on at least one first memory module, which is coupled to the memory controller in a daisy-chained configuration. A first integrated circuit buffer device is included on the module. The system has a second set of nonvolatile memory devices defining a second memory hierarchy. The second set of nonvolatile memory devices are disposed on at least one second memory module, which is coupled to the at least one first memory module in a daisy-chained configuration. The second module includes a second integrated circuit buffer device. The system is configured such that signals transmitted between the memory controller and the second memory hierarchy pass through the first memory hierarchy.