Riak is an open source, distributed database. Riak is architected for:

* Low-Latency
Riak is designed to store data and serve requests predictably and quickly, even
during peak times.

* Availability
Riak replicates and retrieves data intelligently, making it available for read
and write operations even in failure conditions.

* Fault-Tolerance
Riak is fault-tolerant so you can lose access to nodes due to network partition
or hardware failure and never lose data.

* Operational Simplicity
Riak allows you to add machines to the cluster easily, without a large
operational burden.

WWW: http://basho.com/riak