A Scalable File Replication Scheme for the World Wide Web
University of Tennessee
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The World Wide Web has reached the point where many popular file
servers are overloaded, resulting in degradation or unavailability
of service. Users are also often separated over a small-bandwidth
pipe from a file server they need to access, resulting in
poor response time.
The Bulk File Distribution (BFD) system described in this paper
aims to alleviate these problems by providing mechanisms
for registering and looking up alternative locations for
replicated files. The system also includes authentication and
integrity checking mechanisms. Unlike other proposed name
resolution systems, BFD provides a straightforward consistency
model for updates through the use of an intermediate file handle
that unambiguously identifies a particular sequence of bytes.
We describe a strategy for a gradual transition from using
URLs to using location-independent names which achieves the
benefits of replication while retaining the familiar URL syntax.
We also describe a service called SONAR that is intended to
assist client programs in choosing among alternative locations
for a file, based on a proximity measure. Finally, we
describe a prototype implementation
of the BFD system.