Check out the new USENIX Web site.

Home About USENIX Events Membership Publications Students
FAST 2002 Abstract

Safety, Visibility, and Performance in a Wide-Area File System

Minkyong Kim, Landon P. Cox, and Brian D. Noble, Electrical Engineering and Computer Science University of Michigan


As mobile clients travel, their costs to reach home filing services change, with serious performance implications. Current file systems mask these performance problems by reducing the safety of updates, their visibility, or both. This is the result of combining the propagation and notification of updates from clients to servers.

Fluid Replication separates these mechanisms. Client updates are shipped to nearby replicas, called WayStations, rather than remote servers, providing inexpensive safety. WayStations and servers periodically exchange knowledge of updates through reconciliation, providing a tight bound on the time until updates are visible. Reconciliation is non-blocking, and update contents are not propagated immediately; propagation is deferred to take advantage of the low incidence of sharing in file systems.

Our measurements of a Fluid Replication prototype show that update performance is completely independent of wide-area networking costs, at the expense of increased sharing costs. This places the costs of sharing on those who require it, pre-serving common case performance. Furthermore, the benefits of independent update outweigh the costs of sharing for a work load with substantial sharing. A trace-based simulation shows that a modest reconciliation interval of 15 seconds can eliminate 98% of all stale accesses. Furthermore, our traced clients could collectively expect availability of five nines, even with deferred propagation of updates.

  • View the full text of this paper in PDF and PostScript. Until January 2003, you will need your USENIX membership identification in order to access the full papers.
    The Proceedings are published as a collective work, © 2002 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.

  • If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site.

  • To become a USENIX Member, please see our Membership Information.

?Need help? Use our Contacts page.

Last changed: 27 Dec. 2001 ml
Technical Program
FAST 2002 Home