Oracle RAC on extended clusters provides higher availability than is possible with local Oracle RAC configurations, but an extended cluster may not fulfill all of the disaster-recovery requirements of your organization. If you choose to implement this architecture, you must assess whether this architecture is a good solution for your business, especially considering distance, latency, and the degree of protection it provides. For availability reasons, the data must be located at both sites, thus requiring the implementation of disk mirroring technology for storage. In an extended cluster, the nodes in the cluster are typically dispersed, geographically, such as between two fire cells, between two rooms or buildings, or between two different data centers or cities. However, you can configure Oracle RAC on an Oracle Extended Cluster, which is an architecture that provides extremely fast recovery from a site failure and allows for all nodes, at all sites, to actively process transactions as part of a single database cluster. Traditionally, an Oracle RAC environment is located in one data center. In Oracle RAC, each Oracle instance must run on a separate server.įigure 1-1 Oracle Database with Oracle RAC Architectureĭescription of "Figure 1-1 Oracle Database with Oracle RAC Architecture" If your database applications require vendor clusterware, then you can use such clusterware in conjunction with Oracle Clusterware if that vendor clusterware is certified for Oracle RAC.įigure 1-1 shows how Oracle RAC is the Oracle Database option that provides a single system image for multiple servers to access one Oracle database. Oracle Clusterware is the only clusterware that you need for most platforms on which Oracle RAC operates. Oracle Clusterware along with Oracle Automatic Storage Management (Oracle ASM) (the two together comprise the Oracle Grid Infrastructure) enables you to create a clustered pool of storage to be used by any combination of non cluster and Oracle RAC databases. In addition, Oracle Clusterware enables both non-cluster Oracle databases and Oracle RAC databases to use the Oracle high-availability infrastructure. Oracle Clusterware also manages resources, such as Virtual Internet Protocol (VIP) addresses, databases, listeners, services, and so on. Oracle Clusterware is a required component for using Oracle RAC that provides the infrastructure necessary to run Oracle RAC. Oracle Clusterware is a portable cluster management solution that is integrated with Oracle Database. Oracle RAC uses Oracle Clusterware for the infrastructure to bind multiple servers so they operate as a single system. The Oracle RAC option with Oracle Database enables you to cluster Oracle databases. The combined processing power of the multiple servers can provide greater throughput and Oracle RAC scalability than is available from a single server.Ī cluster comprises multiple interconnected computers or servers that appear as if they are one server to end users and applications. Oracle RAC databases differ architecturally from non-cluster Oracle databases in that each Oracle RAC database instance also has:Īt least one additional thread of redo for each instance All database instances must use the same interconnect, which can also be used by Oracle Clusterware. An Oracle RAC database can have several instances, all of which access one database. Oracle RAC environments, however, have a one-to-many relationship between the database and instances. Non-cluster Oracle databases have a one-to-one relationship between the Oracle database and the instance. This topic provides an introduction to Oracle RAC and its functionality.
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