Storage Class Memories

Description

We are investigating the use of storage class memory (SCM) to build faster, more reliabile storage systems. SCM are non-volatile memory technologies that are capable of replacing hard disks introduced by IBM. Flash memory can be considered as an early version of SCM. Phase-Change RAM(PRAM) is one of the several memory technologies that promises speed and density comparable to DRAM. Our current research focuses on reliable, high performance file system for SCM and new file system access paradigms.

Status

We are currently focusing on reliable file systems for flash memory and non-volatile memory. Our new flash file system, RCFFS, has increased reliability by integrating two-level parities and signature while not sacrificing both performance and space efficiency by eliminating internal fragmentation within a page and using compression for data blocks. We have also explored further about the erasure-coded stripes to increase reliability and lifetime of flash memory based storage systems. We are also developing a storage system that exploits either NVRAM or NVRAM-Flash hybrid for better scalability, reliability and performance.

Useful Links

Here are some links relevant to storage class memories.

• Samsung announcement about phase-change RAM, a replacement for flash

Publications

2009

• Yangwook Kang, Ethan L. Miller, Adding Aggressive Error Correction to a High-Performance Flash File System, Proceedings of the 9th ACM/IEEE Conference on Embedded Software (EMSOFT '09), October 2009.
• Kevin Greenan, Darrell D. E. Long, Ethan L. Miller, Thomas Schwarz, Avani Wildani, Building Flexible, Fault-Tolerant Flash-based Storage Systems, Proceedings of the Fifth Workshop on Hot Topics in System Dependability (HotDep 2009), June 2009.
• Jehan-François Pâris, Ahmed Amer, Darrell D. E. Long, Using storage class memories to increase the reliability of two-dimensional RAID arrays, Technical Report UCSC-SSRC-09-04, April 2009.

2008

• Jehan-François Pâris, Darrell D. E. Long, Thomas Schwarz, Ensuring Data Survival on Solid-State Storage Devices, Proceedings of the 1st International Workshop on Storage and I/O Virtualization, Performance, Energy, Evaluation and Dependability, February 2008.

2007

• Sasha Ames, LiFSBrowse: A Visual, User Environment for the Linking File System, Technical Report UCSC-SSRC-07-08, August 2007.
• Kevin Greenan, Ethan L. Miller, PRIMS : Making NVRAM Suitable for Extremely Reliable Storage, short paper in Proceedings of the 3rd Workshop on Hot Topics in System Dependability (HotDep '07), June 2007.
• Timothy Bisson, Scott A. Brandt, Flushing Policies for NVCache Enabled Hard Disks, Technical Report UCSC-SSRC-07-04, May 2007.
• Timothy Bisson, Scott A. Brandt, Reducing Hybrid Disk Write Latency with Flash-Backed I/O Requests, Technical Report UCSC-SSRC-07-03, May 2007.
• Timothy Bisson, Scott A. Brandt, Darrell D. E. Long, A Hybrid Disk-Aware Spin-Down Algorithm with I/O Subsystem Support, Proceedings of the International Performance Conference on Computers and Communication (IPCCC '07), April 2007. Won Best Paper Award.
• Carlos Maltzahn, Nikhil Bobb, Mark W. Storer, Damian Eads, Scott A. Brandt, Ethan L. Miller, Graffiti: A Framework for Testing Collaborative Distributed Metadata, Proceedings in Informatics 21, March 2007, pages 97–111.
• Mark W. Storer, Graffiti Server - Design and Implementation, Technical Report UCSC-SSRC-07-02, January 2007.

2006

• Kevin Greenan, Ethan L. Miller, Reliability Mechanisms for File Systems Using Non-Volatile Memory as a Metadata Store, Proceedings of the 6th ACM & IEEE Conference on Embedded Software (EMSOFT '06), October 2006, pages 178-187.
• Timothy Bisson, Scott A. Brandt, Darrell D. E. Long, NVCache: Increasing the effectiveness of disk spin-down algorithms with caching, Proceedings of the 14th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS 2006), September 2006.
• Sasha Ames, Nikhil Bobb, Kevin Greenan, Owen Hofmann, Mark W. Storer, Carlos Maltzahn, Ethan L. Miller, Scott A. Brandt, LiFS: An attribute-rich file system for storage class memories, Proceedings of the 23rd IEEE / 14th NASA Goddard Conference on Mass Storage Systems and Technologies, May 2006.
• Nikhil Bobb, Damian Eads, Mark W. Storer, Scott A. Brandt, Carlos Maltzahn, Ethan L. Miller, Graffiti: A framework for testing collaborative distributed metadata, Proceedings of the 7th International Workshop on Distributed Data and Structures (WDAS 2006), January 2006.

2005

• Sasha Ames, Nikhil Bobb, Scott A. Brandt, Adam Hiatt, Carlos Maltzahn, Ethan L. Miller, Alisa Neeman, Deepa Tuteja, Richer file system metadata using links and attributes, Proceedings of the 22nd IEEE / 13th NASA Goddard Conference on Mass Storage Systems and Technologies, April 2005.
• Timothy Bisson, Scott A. Brandt, Reducing Energy Consumption with a Non-Volatile Storage Cache, International Workshop on Software Support for Portable Storage (IWSSPS) held in conjunction with the IEEE Real-Time and Embedded Systems and Applications Symposium (RTAS 2005), March 2005.

2004

• Nate Edel, Deepa Tuteja, Ethan L. Miller, Scott A. Brandt, MRAMFS: a compressing file system for non-volatile RAM, Proceedings of the 12th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS '04), October 2004, pages 596-603.
• Nate Edel, Karl Brandt, Ethan L. Miller, Scott A. Brandt, Measuring the compressibility of metadata and small files for disk/nvram hybrid storage systems., Proceedings of the 2004 International Symposium on Performance Evaluation of Computer and Telecommunication Systems (SPECTS '04), July 2004.
• Timothy Bisson, Scott A. Brandt, Adaptive Disk Spin-down Algorithms in Practice, March 2004.

2003

• Nate Edel, Karl Brandt, Ethan L. Miller, Scott A. Brandt, Measuring the compressibility of metadata and small files for disk/NVRAM hybrid storage systems, Technical Report UCSC-CRL-03-04, Storage Systems Research Center, University of California, July 2003.

2002

• Alicja Szczurowska, MRAM–preliminary analysis for file system design, Master's thesis, University of California, Santa Cruz, March 2002, March 2002.

2001

• Ethan L. Miller, Scott A. Brandt, Darrell D. E. Long, HeRMES: High-Performance Reliable MRAM-Enabled Storage, Proceedings of the 8th IEEE Workshop on Hot Topics in Operating Systems (HotOS-VIII), May 2001, pages 83-87.