Seminar: FRASH: Hierarchical File system for Byte Addressable NVRAM and Large Scale Flash Storage

Abstract

In this talk, we introduce our design and implementation experience of hierarchical file system for hybrid storage of FRAM and NAND Flash. We develop state of art file system FRASH which uses byte addressable NVRAM to resolve the drawbacks of the log structured file system for Flash device. Byte addressable NVRAM has very attractive physical characteristics: byte addressability and non-volatility. Due to its capacity limitation, however, we cannot use it as stand-alone storage device under the current state of art technology. We propose to use it as a medium to resolve the fundamental drawbacks of log-structured file system for Flash device. There are three fundamental design considerations in using byte addressable NVRAM as a part of hybrid storage.

First, how should we "view" byte-addressable NVRAM? Block device vs. Main memory. Second, which part of the file system is maintained in byte-addressable NVRAM? Third, What is the right data structure for byte-addressable NVRAM to maintain the file system information? We map byte-addressable NVRAM as part of main memory address space and maintain file metadata and page meta-data in byte addressable NVRAM. Instead of using on-disk data structure, we directly implement DRAM-like data structure in maintaining file system information on byte-address NVRAM. Through this approach, we physically eliminate file system mount phase, speed up the file system I/O and make the file system more reliable to crash. We successfully develop and physically implement FRASH file system on hybrid storage of FRAM(8 MByte) and NAND flash device. It is the first file system which is implemented on physical hybrid storage. 8 MByte FRAM is the largest chip which current state of art technology can afford.

Speaker bio

Youjip Won received BS and MS in Computer Science from Dept. of Computer Science, Seoul National University, in 1990 and 1992, respectively. He received his PhD from Dept. of Computer Science, University of Minnesota in 1997. After graduation, he worked for Intel as server performance analyst. Since March 1999, he has been teaching at Hanyang University, Seoul, Korea where he is now Associate Professor. His research interests include Operating System, Storage System, Multimedia Networking, Intern Traffic Measurement and Modeling.

When:
Monday, January 14, 2008 at 3:30 PM

Where:
E2-506

CRSS Contact:
Miller, Ethan L.

Last modified 24 May 2019