RAC Considerations

Oracle RAC provides tremendous consolidation benefits to database instances and the applications that connect to them. The ability to provide out-of-the-box high availability to applications, coupled with the benefit to scale inside a node (scale-up) or scale across the RAC cluster (scale-out) or both is unparalleled for everyday applications. When you are migrating multiple applications to the Oracle Exadata Database Machine, one of the key decisions you will have to make involves how you isolate instances and clusters. You could use one large RAC cluster for all consolidated applications, which would reduce management overhead and give you the option of allocation of resources through services, described in the next section. You could also choose to migrate each database to its own RAC cluster, which in many ways is the easier path, but which loses some flexibility in allocating resources and a smaller ration of availability with fewer nodes.