The goal of the Swarm project is to design and implement a scalable network storage system based on a cluster of personal computers. Swarm is scalable because its performance is a function of the size of the cluster -- the more nodes in the cluster, the higher the system performance. This performance improvement is not merely an increase in aggregate performance, either; clients whose I/O performance is limited by the storage system will see an improvement in individual I/O operations if more storage servers are added. This decoupling of I/O performance from storage server performance allows the nodes of the cluster to be chosen to optimize cost-performance, rather than absolute performance -- the desired performance of the overall system is attained by aggregating enough nodes.