Long-term digital archiving based on selection of repositories over P2P networks

The importance of digital information is constantly increasing in the last years. Such information often needs to be preserved for a long-term and this is the responsibility of digital archiving systems. This paper proposes a reliable replication model of immutable digital content to be used in long-term archiving systems. The archiving system is modeled as a set of storage repositories where each repository has an independent fail probability assigned to it. Items are inserted with a reliability that is satisfied by replicating them in subsets of repositories. Through simulation, we evaluated three different proposed strategies to create replicas. It is also proposed a completely distributed archiving system using this model over a structured peer-to-peer (P2P) network. The communication between the nodes (repositories) of the network is organized in a distributed hash table and multiple hash functions are used to select repositories that will keep the replicas of each stored item. The system is evaluated through experiments in a real environment. The proposed model and the algorithms, combined with the structured P2P scalability made possible the construction of a reliable and totally distributed digital archiving system.