Read Online Oracle Essentials Oracle Database 11g by Rick Greenwald - Free Book Online

invokes the eight steps required for failover.
    In addition to providing physical standby database support, Data Guard can create a logical standby database. In this scenario, Oracle archive logs are transformed into SQL transactions and applied to an open standby database.
    Oracle Database 10 g introduced several new features, including support for real-time application of redo data, integration with the Flashback database feature, and archivelog compression. Starting with Oracle Database 10 g , rolling upgrades are supported. As of Oracle Database 11 g , the Active Data Guard Opton enables the standby database to be used for queries, sorting, and reporting even as changes from the production system are being applied.
    Fail Safe
    The Fail Safe feature provides a higher level of reliability for an Oracle database.
    Failover is implemented through a second system or node that provides access to data residing on a shared disk when the first system or node fails. Oracle Fail Safe for Windows, in combination with Microsoft Cluster Services, provides a failover solution in the event of a system failure.
    Fail Safe is primarily a disaster recovery tool, so some downtime does occur as part of a failover operation. The recommended solution for server availability, since Oracle9 i , is Real Application Clusters.
    Oracle Real Application Clusters
    Real Application Clusters (RAC) replaced the Oracle Parallel Server (OPS) option beginning with Oracle9 i . RAC can provide failover support as well as increased scalability on Unix, Linux, and Windows clusters. Key to improved scalability was the introduction of Cache Fusion that greatly minimizes the amount of writing to disk that was formerly used to control data locks. Oracle Database 10 g introduced a new level of RAC portability and Oracle support by providing integrated “clusterware” for the supported RAC platforms.
    With Real Application Clusters, you can deploy multiple Oracle instances on multiple nodes of a clustered solution or in a grid configuration. RAC coordinates traffic among the systems or nodes, allowing the instances to function as a single database.
    As a result, the database has proven to scale across dozens of nodes. Since the cluster provides a means by which multiple instances can access the same data, the failure of a single instance will not cause extensive delays while the system recovers. You can simply redirect users to another instance that’s still operating. Applications can leverage the Oracle Call Interface (OCI) to provide failover to a second instance transparently to the user.
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    Chapter 1: Introducing Oracle

    Data Guard and RAC
    Data Guard and RAC in combination replaced Parallel Fail Safe beginning with Oracle9 i . Data Guard provides automated failover with bounded recovery time in conjunction with Oracle Real Application Clusters. In addition, it provides client rerouting from the failed instance to the instance that is available with fast reconnect and automatically captures diagnostic data.
    Automated Storage Management
    Oracle Database 10 g introduced Automated Storage Management (ASM), which provides optimum striping and mirroring of data for performance and availability.
    Because ASM is managed through Enterprise Manager, the database administrator now can perform this critical management task. The need to coordinate this activity with a system administrator is thus greatly reduced.
    Real Application Testing Option
    Oracle Database 11 g introduced the capability to rerun production workloads and test system changes through the Real Application Testing Option. This database option includes a Database Replay facility and the SQL Performance Analyzer. Database Replay captures production workload information, including concurrency, dependencies, and timing. It transforms the workload capture files into replay files, provides a Replay Client for processing the replay files, and provides the means to report on performance statistics and any