Toward Fault-tolerant P2P Systems: Constructing a Stable Virtual Peer from Multiple Unstable Peers

Kota Abe, Tatsuya Ueda, Masanori Shikano, Hayato Ishibashi and Toshio Matsuura: Toward Fault-tolerant P2P Systems: Constructing a Stable Virtual Peer from Multiple Unstable Peers, In Proceeding of International Conference on Advances in P2P Systems (AP2PS 2009), pp.104–110, (Oct. 2009). (Best Paper Award)

Abstract

P2P systems must handle unexpected peer failure and leaving, and thus it is more difficult to implement than server-client systems. In this paper, we propose a novel approach to implement P2P systems by using virtual peers. A virtual peer consists of multiple unstable peers. A virtual peer is a stable entity; application programs run on a virtual peer are not compromised unless a majority of the peers fail within a short time duration. If a peer in a virtual peer fails, the failed peer is replaced by another (non-failed) one to restore the number of working peers.

The primary contribution of this paper is to propose a method to form a stable virtual peer over multiple unstable peers. The major challenges are to maintain consistency between multiple peers and to replace a failed peer with another one. For the first issue, the Paxos consensus algorithm is used. For the second issue, the process migration technique is used to replicate and transfer a running process to a remote peer. Furthermore, the relation between the reliability of a virtual peer and the number of peers assigned to a virtual peer is evaluated.

The proposed method is implemented in our musasabi P2P platform. An overview of musasabi and its implementation is also given.

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