An empirical study of deploying storage class memory into the I/O path of portable systems

We explore the possibility of deploying storage class memory (SCM) into the I/O path as a file system metadata store and examine what effects it has on the performance of portable computing systems. In this regard, we develop a new flash memory-based file system that stores all metadata in SCM, while storing all file data in flash memory. In so doing, we make two contributions in this work. First, we present a model that analyzes the amount of SCM that is needed for specific flash memory storage capacity. Second, we present quantitative experimental results that show how much performance gains are possible by exploiting SCM in terms of I/O performance, energy efficiency and lifetime of the underlying flash memory. Compared to YAFFS, a popular flash memory-based file system, we show that system performance is improved by a maximum of around 320, 260, and 180 in terms of I/O performance, energy efficiency and lifetime of the Flash memory, respectively, for the realistic workloads that we considered.