In this work we tackle the problem of online backup and storage with a peer-to-peer approach. We propose a novel system architecture involving the users' devices that confederate by pooling their resources and offer an alternative to capital-intensive data-centers. In contrast to current peer-to-peer architectures that build upon distributed hash-tables, we investigate whether an uncoordinated approach to data placement would prove effective in providing embedded incentives for users to offer local resources to the system. By modeling peers as selfish entities striving for minimizing their cost in participating to the system, we analyze equilibrium topologies that materialize from the process of peer selection, whereby peers establish bi-lateral links that involve storing data in a symmetric way. System stratification, colluding peers with similar contribution efforts, is an essential outcome of the peer selection process: peers are lured to improve the "quality" of local resources they provide to reach lower operational costs. Our results are corroborated by both a game-theoretic analysis and a numerical evaluation of several system configurations.
