Design and analysis of a space conscious nonvolatile-RAM file system

Abstract

Nonvolatile memory technology is evolving continuously and commercial products such as FeRAM and PRAM are now appearing in the market. As Nonvolatile-RAM (NVRAM) has properties of both memory and storage, it can store persistent data objects while allowing fast and random access. To utilize NVRAM for general purpose storing of frequently updated data across power disruptions, some essential features of the file system including naming, recovery, and space management are required while exploiting memory-like properties of NVRAM. Conventional file systems, including even recently developed NVRAM file systems, show very low space efficiency wasting more than 50% of the total space in some cases. To efficiently utilize the relatively expensive NVRAM, we design and analyze a new extent-based file system, which we call NEBFS (NVRAM Extent-Based File System). We analyze and compare the space utilization of conventional file systems with NEBFS.