The invention provides improved data processing apparatus, systems and methods that include one or more nodes, e.g., processor modules or otherwise, that include or are otherwise coupled to cache, physical or other memory (e.g., attached flash drives or other mounted storage devices) collectively, “system memory.” At least one of the nodes includes a cache memory system that stores data (and/or instructions) recently accessed (and/or expected to be accessed) by the respective node, along with tags specifying addresses and statuses (e.g., modified, reference count, etc.) for the respective data (and/or instructions). The tags facilitate translating system addresses to physical addresses, e.g., for purposes of moving data (and/or instructions) between system memory (and, specifically, for example, physical memory—such as attached drives or other mounted storage) and the cache memory system.