I was in Chicago all week taking the RAC class. It’s new in Oracle 9. It is a complete rewrite of Oracle Parallel Server. There were excellent lab exercises – we each build a cluster and tested failure of one node. I had a long select running and stopped the node where it was running. The output paused a few seconds then started back up where it left off. This early version only runs on Sun and only uses raw files. We have been clustering databases for high availability for a long time. I think the market for RAC is going to be for databases where you can’t get a box big enough for the load. This lets you add more boxes to increase the cpu and memory available to Oracle.