A memory system that has a multi-channel volatile memory subsystem is coupled to a non-volatile memory subsystem to provide independent, configurable backup of data. The volatile memory subsystem has one or more main memory modules that use a form of volatile memory such as DRAM memory, for which the NV subsystem provides selective persistent backup. The main memory modules are dual in-line memory modules or DIMMs using DDR SDRAM memory devices. The non-volatile memory subsystem (NV backup) includes an NV controller and non-volatile memory NVM. The NV backup can also include a memory cache to aid with handling and storage of data. In certain embodiments, the NV controller and the non-volatile memory are coupled to the one or more DIMM channels of the main memory via associated signal lines. Such signal lines can be, for example, traces on a motherboard, and may include one or more signal buses for conveying data, address, and/or control signals. The NV controller and the non-volatile memory can be mounted on the motherboard.