Improving data availability in chord p2p system

In this paper we investigate the information availability in the direct union of 2 copies of chord which is the improved version of popular P2P Chord system. We present precise asymptotic formula describing the resistance to the loss of documents stored in them. After unexpected departures of $k=o(\sqrt{n})$ nodes from the system no information disappears with high probability probability and $\sqrt{n}=o(k)$ unexpected departures lead to loss some data with high probability. Our modification of Chord is very soft and requires only a small interference in the programming code of the original Chord protocol.