Highly redundant management of distributed data

An algorithm for redundant management of distributed data using a minimal amount of data replication is described and analyzed. The main results on storage space utilization, I/O (input/output) performance, and reliability are outlined. The recently introduced RAID (redundant array of inexpensive disks) concept is extended to a distributed computing system. The resulting distributed storage architecture, called RADD (redundant array of distributed disks), is shown to support redundant copies of data across a computer network at the same space cost as RAIDs do for local data. Thus, a RADD increases data availability in the presence of both temporary and permanent failures (disasters) at local sites. During normal operation, the RADD scheme offers performance comparable to the two-copies systems. As such, RADDs should be considered a possible alternative to traditional multiple-copy techniques as well as to other high-availability schemes