Ingres has launched its Project Icebreaker, which consists of a minimal GNU/Linux operating system featuring only what is needed to run the Open Source Ingres 2006 database server. All the package is licensed under the GPL, and annual support contracts are proposed. More questions about the product are answered by the FAQ. It should be available for download shortly.

Ingres is one of the most mature RDBMS, having spawned other systems such as Postgresql