Operational Database Management Systems
Voldemort’s local persistence component allows for different storage engines to be plugged in. This software creates a new storage engine that uses db4o as storage engine in Voldemort. The source code is available under...
Hypertable: Modeled after Google’s Bigtable project, Hypertable is an open source software designed to manage the storage and processing of information on a large cluster of commodity servers, providing resilience to machine and component failures....
Databeans is a fully object oriented persistence framework for java, based on the use of javabeans accessor methods to read/write data on disk in place of in class instance fields, available under GPL. LINK