The active-active architecture of Oracle RAC (or Oracle RAC on Extended Clusters for on-premise only) provides a number of advantages for the MAA Silver reference architecture:
- Improved high availability If a server or database instance fails, connections to surviving instances are not affected; connections to the failed instance are quickly failed over to surviving instances that are already running and open on other servers in the Oracle RAC cluster.
- Scalability Oracle RAC is ideal for high volume applications or consolidated environments where scalability and the ability to dynamically add or re-prioritize capacity across more than a single server are required. An individual database may have instances running on one or more nodes of a cluster. Similarly, a database service may be available on one or more database instances. Additional nodes, database instances, and database services can be provisioned online. The ability to easily distribute workload across the cluster makes Oracle RAC the ideal complement for Oracle Multitenant when consolidating many databases.
- Reliable performance in consolidated database environments can be delivered by using Oracle Quality of Service (QoS) to allocate capacity for high priority database services. Capacity can be dynamically shifted between workloads to quickly respond to changing requirements.
- High availability maintained during planned maintenance by implementing changes in a rolling manner across Oracle RAC nodes. This includes database, hardware, operating system, or network maintenance that requires a server or database instance to be taken offline or restarted; software maintenance to update or patch the database or Oracle Grid Infrastructure; or moving a database instance to another server to increase capacity or balance the workload.
- Application Failover Practices or Application Continuity mask recoverable outages and Oracle RAC rolling planned maintenance activities in the application tier by draining and relocating connections and optionally replaying application requests at another available Oracle RAC instance. With application checklist practices, Oracle recommends simple non-intrusive application changes that include 1) using Oracle services, 2) modifying connection strings, and 3) enabling fast application notification and draining. Optionally enabling application continuity or transparent application continuity (TAC) requires some additional application investment to reap benefits of application replay after failure. For steps and guidance, see Continuous Availability - Application Checklist for Continuous Service for MAA Solutions.
- Oracle Clusterware, grouped with Oracle Automatic Storage Management (ASM) as Oracle Grid Infrastructure, is the integrated foundation for Oracle Real Application Clusters and the high availability and resource management framework for all applications on any major platform supported for Oracle RAC.
- Site Failure and limited DR protection (Oracle RAC on Extended Clusters only) is provided when a single database consisting of Oracle RAC nodes is spread across multiple data centers. Due to its incomplete DR protection, Oracle RAC on Extended Clusters is not available in any Oracle cloud solutions. If a site failure occurs with an Oracle RAC on Extended Clusters architecture (also known as Oracle Stretched RAC or Oracle Extended RAC), the application can transparently fail over to surviving Oracle RAC nodes and instances in the other sites. To ensure stability and performance, Oracle RAC on Extended Clusters requires low network latency (less than 1 ms) and high network bandwidth (10 GigE or higher) for Oracle RAC interconnect. An additional storage quorum device in a third site and Oracle ASM Extended Disk Groups are required. Oracle RAC on Extended Clusters gives you the benefits of Oracle RAC but does not comprehensively address disaster recovery. Oracle MAA recommends adding Oracle Data Guard to complete the Gold MAA architecture so that other unplanned outages such as data corruptions, database failures, cluster failures, and regional failures are covered.
MAA Silver requires Oracle Database Enterprise Edition, Oracle RAC, and Oracle Enterprise Manager life-cycle, management, diagnostic, and tuning packs for on-premises databases. Oracle RAC One-Node is an option for active-passive high availability if scalability is not required, and your environment can tolerate slightly higher recovery time for database and Oracle RAC instance failures.
Optionally, you can enhance your high availability architecture by using these recommended features and capabilities:
For more information about Oracle capabilities used in this MAA reference architectures click on the objects in the graphic above.
Learn more about Oracle MAA blueprints for reduced planned and unplanned downtime for Oracle Database on-premises, on Exadata Database Machine, and on Oracle Cloud.