Date Added: Jan 2012
The authors propose a redundancy management mechanism for peer-to-peer backup applications. Since, in a backup system, data is read over the network only during restore processes caused by data loss, redundancy management targets data durability rather than attempting to make each piece of information available at any time. Each peer determines, in an on-line manner, an amount of redundancy sufficient to counter the effects of peer deaths, while preserving acceptable data restore times. Their experiments, based on trace-driven simulations, indicate that their mechanism can reduce the redundancy by a factor between two and three with respect to redundancy policies aiming for data availability.