Abstract
Peer-to-peer storage systems aim to provide a reliable long-term storage at low cost. In such systems, peers fail continuously, hence, the necessity of
self-repairing mechanisms to achieve high durability. In this paper, we propose
and study analytical models that assess the bandwidth consumption
and the probability to lose data of storage systems that use erasure
coded redundancy. We show by simulations that the classical stochastic approach
found in the literature, that models each block independently, gives a correct
approximation of the system average behavior, but fails to capture its
variations over time. These variations are caused by the simultaneous loss of
multiple data blocks that results from a peer failing (or leaving the system).
We then propose a new stochastic model based on a fluid approximation that
better captures the system behavior. In addition to its expectation, it gives a
correct estimation of its standard deviation. This new model is validated by simulations.
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