Coding In Paradise

Confessions of an operating systems junkie: "Surely you are familiar with all those peer-to-peer systems papers motivated by greed-tinged descriptions of gigabytes of unused disk space just waiting to be used on people's personal computers? Charles Blake was skeptical of a world where unused storage falls like manna from the sky, so he created a few models and looked at some real-world data. It turns out that with realistic node membership times, member node bandwidths, and number of data copies necessary to provide reasonable availability, the amount of data that can be stored in a peer-to-peer network is severely limited by cross-network bandwidth, rather than available disk space. Blake puts it all so much more politely in his paper, with sentences like 'We conclude that when redundancy, data scale, and dynamics are all high, the requisite cross-system bandwidth is beyond reasonable expectations.'"