Capsule: an energy-optimized object storage system for memory-constrained sensor devices

ABSTRACT

Recent gains in energy-efficiency of new-generation NAND flash storage have strengthened the case for in-network storage by data-centric sensor network applications. This paper argues that a simple file system abstraction is inadequate for realizing the full benefits of high-capacity lowpower NAND flash storage in data-centric applications. Instead we advocate a rich object storage abstraction to support flexible use of the storage system for a variety of application needs and one that is specifically optimized for memory and energy-constrained sensor platforms. We propose Capsule, an energy-optimized log-structured object storage system for flash memories that enables sensor applications to exploit storage resources in a multitude of ways. Capsule employs a hardware abstraction layer that hides the vagaries of flash memories for the application and supports energy-optimized implementations of commonly used storage objects such as streams, files, arrays, queues and lists. Further, Capsule supports checkpointing and rollback of object states to tolerate software faults in sensor applications running on inexpensive, unreliable hardware. Our experiments demonstrate that Capsule provides platform-independence, greater functionality, more tunability, and greater energy-efficiency than existing sensor storage solutions, while operating even within the memory constraints of the Mica2 Mote. Our experiments not only demonstrate the energy and memory-efficiency of I/O operations in Capsule but also shows that Capsule consumes less than 15% of the total energy cost in a typical sensor application.

REFERENCES

• 1: T. Blackwell, J. Harris, , and M. Seltzer. Heuristic cleaning algorithms in Log-structured File Systems. In USENIX Winter Conf, pages 277--288. Jan 1995.
• 2: MicaSB Sensor board MTS 300. www.xbow.com.
• 3: Hui Dai , Michael Neufeld , Richard Han, ELF: an efficient log-structured flash file system for micro sensor nodes, Proceedings of the 2nd international conference on Embedded networked sensor systems, November 03-05, 2004, Baltimore, MD, USA [doi>10.1145/1031495.1031516]
• 4: E. Gal and S. Toledo. A transactional flash file system for microcontrollers. In USENIX , pages 89--104, Anaheim CA, Apr 2005.
• 5: D. Gay. Design of Matchbox: The simple Filing system for Motes. In TinyOS 1.x distribution, www.tinyos.net, Aug 2003.
• 6: J. Hellerstein, W. Hong, S. Madden, and K. Stanek. Beyond Average: Towards sophisticated sensing with Queries. In IPSN, Palo Alto CA, 2003.
• 7: Jonathan W. Hui , David Culler, The dynamic behavior of a data dissemination protocol for network programming at scale, Proceedings of the 2nd international conference on Embedded networked sensor systems, November 03-05, 2004, Baltimore, MD, USA [doi>10.1145/1031495.1031506]
• 8: P. Levis, S. Madden, J. Polastre, et al. TinyOS: An Operating System for wireless Sensor networks. In Ambient Intelligence. Springer-Verlag, 2005.
• 9: M. Li, D. Ganesan, and P. Shenoy. PRESTO: Feedback-driven Data management in Sensor networks. In NSDI, May 2006.
• 10: Samuel R. Madden , Michael J. Franklin , Joseph M. Hellerstein , Wei Hong, TinyDB: an acquisitional query processing system for sensor networks, ACM Transactions on Database Systems (TODS), v.30 n.1, p.122-173, March 2005 [doi>10.1145/1061318.1061322]
• 11: Gaurav Mathur , Peter Desnoyers , Deepak Ganesan , Prashant Shenoy, Ultra-low power data storage for sensor networks, Proceedings of the fifth international conference on Information processing in sensor networks, April 19-21, 2006, Nashville, Tennessee, USA [doi>10.1145/1127777.1127833]
• 12: Jeanna Neefe Matthews , Drew Roselli , Adam M. Costello , Randolph Y. Wang , Thomas E. Anderson, Improving the performance of log-structured file systems with adaptive methods, Proceedings of the sixteenth ACM symposium on Operating systems principles, p.238-251, October 05-08, 1997, Saint Malo, France
• 13: A. Mitra, A. Banerjee, W. Najjar, D. Zeinalipour-Yazti, D. Gunopulos, and V. Kalogeraki. High-Performance, Low-Power sensor platforms featuring Gi-gabyte scale Storage. In SenMetrics, San Diego CA, Jul 2005.
• 14: E.B. Nightingale and J. Flinn. Energy-efficiency and Storage Flexibility in the Blue file system. In OSDI, San Francisco CA, Dec 2004.
• 15: K. Nrvag. Vagabond: The design and analysis of a Temporal Object database management system. PhD thesis - Norwegian University of Science and Technology, 2000.
• 16: Joseph Polastre , Jason Hill , David Culler, Versatile low power media access for wireless sensor networks, Proceedings of the 2nd international conference on Embedded networked sensor systems, November 03-05, 2004, Baltimore, MD, USA [doi>10.1145/1031495.1031508]
• 17: Joseph Polastre , Robert Szewczyk , David Culler, Telos: enabling ultra-low power wireless research, Proceedings of the 4th international symposium on Information processing in sensor networks, April 24-27, 2005, Los Angeles, California
• 18: Nithya Ramanathan , Kevin Chang , Rahul Kapur , Lewis Girod , Eddie Kohler , Deborah Estrin, Sympathy for the sensor network debugger, Proceedings of the 3rd international conference on Embedded networked sensor systems, November 02-04, 2005, San Diego, California, USA [doi>10.1145/1098918.1098946]
• 19: S. Ratnasamy, D. Estrin, R. Govindan, B. Karp, L.Y.S. Shenker, and F. Yu. Data-centric storage in sensornets. In HotNets, 2001.
• 20: Sylvia Ratnasamy , Brad Karp , Li Yin , Fang Yu , Deborah Estrin , Ramesh Govindan , Scott Shenker, GHT: a geographic hash table for data-centric storage, Proceedings of the 1st ACM international workshop on Wireless sensor networks and applications, September 28-28, 2002, Atlanta, Georgia, USA [doi>10.1145/570738.570750]
• 21: Mendel Rosenblum , John K. Ousterhout, The design and implementation of a log-structured file system, ACM Transactions on Computer Systems (TOCS), v.10 n.1, p.26-52, Feb. 1992 [doi>10.1145/146941.146943]
• 22: Toshiba America Electronic Components, Inc. (TAEC), www.toshiba.com/taec. Datasheet: TC58DVG02A1FT00, Jan 2003.
• 23: John Wilkes , Richard Golding , Carl Staelin , Tim Sullivan, The HP AutoRAID hierarchical storage system, ACM Transactions on Computer Systems (TOCS), v.14 n.1, p.108-136, Feb. 1996 [doi>10.1145/225535.225539]
• 24: D. Woodhouse. Journalling Flash File System. http://sources.redhat.com/jffs2/jffs2.pdf.
• 25: Aleph One. Yet Another Flash File System. www.aleph1.co.uk/yaffs.
• 26: Xbow. Mica2 Data sheet. http://www.xbow.com/Products/Product_pdf_files/Wireless_pdf/6020-0042-0%6_A_MICA2.pdf.
• 27: D. Zeinalipour-Yazti, S. Lin, V. Kalogeraki, D. Gunopulos, and W. Najjar. MicroHash: An efficient Index structure for Flash-based sensor devices. In USENIX FAST, SF CA, Dec 2005.

INDEX TERMS

Primary Classification:
  D. Software
  D.4 OPERATING SYSTEMS
      D.4.2 Storage Management
          Subjects: Secondary storage

Additional Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
        D.2.13 Reusable Software
            Subjects: Reusable libraries

General Terms:
Design, Experimentation, Performance

Keywords:
embedded systems, energy efficiency, file system, flash memory, objects, sensor network, storage system