Understanding Availability
- Ranjita Bhagwan ,
- Stefan Savage ,
- Geoffrey M. Voelker
In Proceedings of the 2nd International Workshop on Peer-to-peer Systems |
Published by Springer Verlag
This paper addresses a simple, yet fundamental question
in the design of peer-to-peer systems: What does it mean
when we say “availability” and how does this understanding
impact the engineering of practical systems? We argue
that existing measurements and models do not capture
the complex time-varying nature of availability in today’s
peer-to-peer environments. Further, we show that unforeseen
methodological shortcomings have dramatically biased
previous analyses of this phenomenon. As the basis of our
study, we empirically characterize the availability of a large
peer-to-peer system over a period of 7 days, analyze the dependence
of the underlying availability distributions, measure
host turnover in the system, and discuss how these results
may affect the design of high-availability peer-to-peer
services.