A cooperative recovery service is an attractive architecture for tolerating Internet catastrophes. It is attractive for both individual Internet users, like home broadband users, who do not wish to pay for commercial backup service or deal with the inconvenience of making manual backups, as well as corporate environments, which often have a significant amount of unused disk space per machine. If Phoenix were deployed, users would not need to exert significant effort to backup their data, and they would not require local backup systems. Phoenix makes specifying what data to protect as straightforward as specifying what data to share on file-sharing peer-to-peer systems. Further, a cooperative architecture has little cost in terms of time and money; instead, users relinquish a small fraction of their disk, CPU, and network resources to gain access to a highly resilient backup service.
As with Pastiche , we envision using Phoenix as a cooperative recovery service for user data. However, rather than exploiting redundant data on similar hosts to reduce backup costs for operating system and application software, we envision Phoenix users only backing up user-generated data and relying upon installation media to recover the operating system and application software. With this usage model, broadband users of Phoenix can recover 10 GB of user-generated data in a day. Given the relatively low capacity utilization of disks in desktop machines , 10 GB should be sufficient for a wide range of users. Further, users can choose to be more selective in the data backed up to reduce their recovery time. We return to the issue of bandwidth consumption and recovery time in Section 7.3.