Keyspace: A Consistently Replicated, Highly-Available Key-Value Store
  This paper describes the design and architecture of Keyspace, a distributed key-value store offering strong consistency, fault-tolerance and high availability. The source code is available under the open-source AGPL license for Linux, Windows and BSD-like platforms. As of 2012, Keyspace is no longer undergoing active development. 
M\'arton Trencs\'eni, Attila Gazs\'o
cs.DB cs.DC