Riak, a scalable and reliable data store, is available in Fedora 15.
Riak is a Dynamo-inspired key/value store, written in Erlang, that scales predictably and easily. Riak also simplifies development by giving developers the ability to quickly prototype, test, and deploy their applications.
A truly fault-tolerant system, Riak has no single point of failure. No machines are special or central in Riak, so developers and operations professionals can decide exactly how fault-tolerant they want and need their applications to be.
has been updated to version 5.5.8. Included are improved scalability and performance. From the release announcement: "Higher availability: New semi-synchronous replication and Replication Heart Beat improve failover speed and reliability."