Oracle Real Application Clusters (RAC) 11g Release 2
Oracle Real Application Clusters (RAC) allows Oracle Database to run any packaged or custom application, unchanged across a server pool. This provides the highest levels of availability and the most flexible scalability. If a server in the pool fails, the Oracle database continues to run on the remaining servers. When you need more processing power, simply add another server to the pool without taking users offline. To keep costs low, even the highest-end systems can be built out of standardized, commodity parts. Read on.