NVMTFS: A Non-Volatile Memory Adaptive File System for Tiered Storage System

Abstract

Tiered storages have been widely used for large scale data to achieve high read/write performance while keeping low costs. However, most of their managements are implemented in block level and it is transparent to file system and high level applications, which cannot have clean and accurate information about data usage and temperature. Thereby there may be low performance and high resources usage. In this paper, we propose a new file system — NVMTFS, which is NVM adaptive and achieves file system level data management for tiered storage. NVM replaces DRAM as the whole system memory, such that part of the data and metadata can be permanently stored on NVM without flushing back to tiered storage. NVMTFS uses NVM not only as memory, but also a ghost tier to store data, there will be no data duplication between NVM and tiered storage. More accurate and less migration operation can be achieved in NVMTFS by using NVM as one more tier and no cache tier in the system. We have designed NVMTFS and described its system architecture, file system layout and data operation. NVMTFS shows its great potential for tiered storage to store big data while guaranteeing read/write performance. In the future, the prototype will implemented within a Linux Kernel and its performance can be compared with other file system such as EXT3, btrfs, NILFS2 and NVMFS.