Database HA/DR Service includes setting up Oracle Data Guard, setting up Oracle Real Application Cluster, setting up and implementing the Disaster Recovery solutions. This is the most important tasks to protect the databases.
- Oracle Data Guard
Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data. Oracle Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruptions. Oracle Data Guard maintains these standby databases as copies of the production database. Then, if the production database becomes unavailable because of a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage. Oracle Data Guard can be used with traditional backup, restoration, and cluster techniques to provide a high level of data protection and data availability. Oracle Data Guard transport services are also used by other Oracle features such as Oracle Streams and Oracle GoldenGate for efficient and reliable transmission of redo from a source database to one or more remote destinations.
With Oracle Data Guard, administrators can optionally improve production database performance by offloading resource-intensive backup and reporting operations to standby systems. (source : http://docs.oracle.com)
- Oracle Real Application Cluster
Noncluster Oracle databases have a one-to-one relationship between the Oracle database and the instance. Oracle RAC environments, however, have a one-to-many relationship between the database and instances. An Oracle RAC database can have up to 100 instances, all of which access one database. All database instances must use the same interconnect, which can also be used by Oracle Clusterware.
Oracle RAC databases differ architecturally from noncluster Oracle databases in that each Oracle RAC database instance also has:
- At least one additional thread of redo for each instance
- An instance-specific undo tablespace
The combined processing power of the multiple servers can provide greater throughput and Oracle RAC scalability than is available from a single server.
A cluster comprises multiple interconnected computers or servers that appear as if they are one server to end users and applications. The Oracle RAC option with Oracle Database enables you to cluster Oracle databases. Oracle RAC uses Oracle Clusterware for the infrastructure to bind multiple servers so they operate as a single system.
Oracle Clusterware is a portable cluster management solution that is integrated with Oracle Database. Oracle Clusterware is a required component for using Oracle RAC that provides the infrastructure necessary to run Oracle RAC. Oracle Clusterware also manages resources, such as Virtual Internet Protocol (VIP)addresses, databases, listeners, services, and so on. In addition, Oracle Clusterware enables both noncluster Oracle databases and Oracle RAC databases to use the Oracle high-availability infrastructure. 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 noncluster and Oracle RAC databases.
Oracle Clusterware is the only clusterware that you need for most platforms on which Oracle RAC operates. 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. (source : http://docs.oracle.com)
- Disaster Recovery
Disaster Recovery is a strategic response to the loss of all data associated with a database installation. For example, a fire may destroy a server in a data center, forcing you to reinstall Oracle Database on a new server and recover the lost database from backups. (source : http://docs.oracle.com)