just learned about RAIDb
RAIDb stands for Redundant Array of Inexpensive Databases. This acronym has been used in reference to the RAID (Redundant Array of Inexpensive Disks) concept that achieves scalability and high availability of disk subsystems at a low cost. RAIDb aims at providing better performance and fault tolerance than a single database by combining multiple inexpensive database instances into an array of databases.
C-JDBC is a database cluster middleware that implements RAIDb, LGPL licensed.