As computer systems evolve towards exascale and attempt to meet new application requirements such as big data, conventional memory technologies and architectures are no longer adequate in terms of bandwidth, power, capacity, or resilience. In order to understand these problems and analyze potential solutions, an accurate simulation environment that captures all of the complex interactions of the modern computer system is essential. This paper presents an integrated simulation infrastructure for the entire memory hierarchy, including the processor cache, the DRAM main memory system, and nonvolatile memory, whether it is integrated as hybrid main memory or as a solid state drive.