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Projects: VAFS

AFS for Very High Speed Networks

Principal Investigator:  Charles J. Antonelli
Center for Information Technology Integration
The University of Michigan

Project Period:  1 October 1998 - 1 February 2000

CITI, in partnership with the  Naval Research Laboratory,  is engaged in a research project to augment AFS for very high speed networks:

  • Selective-caching client, for efficient access to continuous media stored in AFS
  • Split-path AFS, to provide high speed data access over ATM

Selective-Caching Client

Statement of Work

This project will implement and demonstrate a modified AFS Cache Manager that selectively caches files to the AFS client local disk.  With caching disabled, AFS file data arriving from a file server are given immediately to the requesting application, and are never cached on the client's local disk.  This improves the performance of continuous media applications (such as streaming video players) when the network is faster than the local disk by eliminating disk latencies from the data processing pipe. As a secondary benefit, selective caching frees client processor and cache resources for use by applications for which local caching is an advantage.

We will demonstrate this work by playing video through a modified cache manager that supports cached and uncached AFS access. This will highlight the performance improvements that accrue to both the streaming video application and to other applications running on the client host.

Split-Path AFS

Statement of Work

We propose to augment the conventional UDP/IP connection between AFS client and server with a "fast path" over ATM  for bulk data transfers.  With split-path AFS enabled, file contents travel between file server and client over an ATM AAL5 connection for greatly improved bandwidth and latency, compared to conventional IP-based networks.

We will demonstrate this work by playing video with split-path processing turned off, and then with split-path on, highlighting the performance improvements that accrue both to the streaming video application as well as to other applications running on the client host, which benefit when the video data no longer competes on the commodity network with other data.

Final Report

TR 01-3 Charles J. Antonelli, Kevin Coffman, and Jim Rees, "Improving AFS Performance via Selective Caching and Native ATM AAL5," February 2001.

Bibliography of Selected CITI Publications

CITI began using AFS in 1988, under the aegis of an IBM-sponsored Institutional File System project (IFS), and immediately began a research program based on AFS technology. Some of our accomplishments include:

  • NFS/AFS translator
  • Appleshare/AFS translator
  • Comprehensive server logging facilities
  • RX performance enhancements
  • AFS security enhancements
  • AFS client performance enhancements
  • Disconnected and partially-connected operation for AFS clients

Some of CITI's AFS enhancements were imported into the AFS product.  Others are in active use at CITI and elsewhere, and continue to be supported by us.

These activities produced two Ph.D.s, Dr. Daniel Muntz and Dr. Larry Huston, influenced the doctoral research of Dr. David Bachmann, Dr. Aviel Rubin, and Dr. A. Masud Khandker, and yielded an extensive collection of CITI technical reports and external publications directly related to AFS:

TR 90-2 P. Honeyman, C.J. Antonelli, and W.A. Doster, "Access Control in a Workstation-Based Distributed Computing Environment," April 1990. [Proc. IEEE Workshop on Experimental Dist. Systems, Huntsville (October 1990).]

TR 90-4 Honeyman, P., "Synopsis of File System Protocols," August 1990.

TR 91-2 C.J. Antonelli, S.R. Burling and L. Pearson, "Measuring IFS AIX/370 File System Performance in LPAR Mode," April 1991.

TR 91-3 P. Honeyman and D.A. Muntz, "Multilevel Caching in Distributed File Systems," August 1991. [Proc. Winter USENIX Conf., San Francisco (January 1992).]

TR 91-4 P. Honeyman, L.B. Huston, and M.T. Stolarchuk, "Hijacking AFS", August 1991. [Proc. Winter USENIX Conf., San Francisco (January 1992).]

TR 91-5 P. Honeyman, "Taking a Little Work Along," August 1991.

TR 92-1 W.A. Doster and J. Rees, "Third-Party Authentication in the Institutional File System," February 1992.

TR 92-3 M.T. Stolarchuk, "Faster AFS," June 1992. [Proc. AFS Users Group, Pittsburgh (Spring 1992).]

TR 92-4 J. Howe, "Intermediate File Servers in a Distributed File System Environment," June 1992.

TR 92-6 R. Subramanian, "Workload Characterization of AFS File Servers," November 23, 1992.

TR 92-7 S. Blumson, "AFS Write Performance - A Campaign Paper," December 10, 1992.

TR 93-2 C.J. Antonelli and P. Honeyman, "Integrating Mass Storage and File Systems," April 1993. [Proc. Twelfth IEEE Symp. on Mass Storage Systems, Monterey (April 1993).]

TR 93-3 L.B. Huston and P. Honeyman, "Disconnected Operation for AFS," June 1993. [Proc. USENIX Symp. on Mobile and Location-Independent Computing, Cambridge (August 1993).]

TR 93-5 T. Hacker, "The Design and Implementation of an AFP/AFS Protocol Translator," August 1993.

TR 93-8 D.W. Bachmann, P. Honeyman, and L.B. Huston, "The Rx Hex," November 1993. [Proc. of IEEE Workshop on Services in Distributed and Networked Environments, Prague (June 1994).]

TR 93-10 S. Blumson, P. Honeyman, T.E. Ragland, and M.T. Stolarchuk, "AFS Server Logging," November 1993.

TR 94-3 S. Blumson, "Workload Characterization in a Large Distributed File System," July 1994.

TR 95-3 L.B. Huston and P. Honeyman, "Peephole Log Optimization," January 1995. [IEEE Comp. Soc. Bull. of the Tech. Comm. on Op. Sys. and Appl. Env. 1:7 (Spring 1995). Presented at IEEE Workshop on Mobile Computing Applications and Systems, Santa Cruz (December 1994).]

TR 95-5 L.B. Huston and P. Honeyman, "Partially Connected Operation," May 1995. [Computing Systems 8(4), pp. 365-379 (Fall 1995). Also Proc. 2nd USENIX Symp. on Mobile and Location-Independent Computing, pp. 91-97, Ann Arbor (April 1995).]

TR 95-9 D.A. Muntz, P. Honeyman, and C.J. Antonelli, "Evaluating Delayed Write in a Multilevel Caching File System," October 1995. [Proc. 2nd Intl. Conf. on Dist. Platforms, pp. 415-429, Dresden (February 1996).]

TR 95-11 P. Honeyman and L.B. Huston, "Communications and Consistency in Mobile File Systems," October 1995. [IEEE Personal Communications (December 1995).] projects | techreports | press | lab | location | staff Email address
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