It also gives users complete control over the routing of change records from the primary database to a replica database. With the Oracle Grid technologies, you can enable a high level of usage and low TCO without sacrificing business requirements. With Oracle Clusterware, you also define an application VIP so that users can access the application independently of the node in the cluster where the application is running. This figure shows Oracle Database with Oracle RAC architecture for a partitioned three-node database. Oracle RAC exploits the redundancy that is provided by clustering to deliver availability with n - 1 node failures in an n-node cluster. In addition to maintaining its own disk block, CSSD processes also monitors the disk blocks maintained by the CSSD processes running in other cluster nodes. In previous releases, technologies like bonding or trunking were used to make use of redundant networks for the interconnect. These updates are discarded when the snapshot database is reconverted to a physical standby database. Flexible and automated high availability solutions ensure that applications you deploy on Oracle Application Server meet the required availability to achieve your business goals. Simulate loss of connectivity between two nodes. Thus, this feature allows you to consolidate many databases into a single cluster for easier management, while still providing high availability by quickly relocating instances in the event of server failure. Start both the services for database admindb so that serv1 executes on host01 and serv2 executes on host02. An Oracle RAC extended cluster 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 single database cluster. Online Patching allows for dynamic database patches for diagnostic and interim patches. Although using Oracle GoldenGate might require additional work, it offers increased flexibility that might be necessary to meet specific business requirements. Another possible configuration might be a testing hub consisting of snapshot standby databases. Applications scale in an Oracle RAC environment to meet increasing data processing demands without changing the application code. See Section 7.1.3, "Oracle Database with Oracle RAC One Node" for more information. Evaluate logical standby databases if additional indexes are required for reporting purposes and if your application only uses data types supported by logical standby database and SQL Apply. Section 7.1.8 describes how you can achieve the highest level of availability with Oracle RAC and Oracle Data Guard. Oracle Database High Availability Best Practices for information about configuring Oracle Database 11g with Oracle RAC on extended clusters, White papers about extended (stretch) clusters and about using standard NFS to support a third voting disk on an extended cluster configuration at http://www.oracle.com/technetwork/database/clustering/overview/. But i want to test it on a test environment in my view for that i need to fail or make the node's to lose connectivity with one another but then continue to . 2. Node Weighting for Split Brain Resolution Without better understanding of what is critical or of higher priority to the customer's workload, Oracle Clusterware has always resolved split brain conditions in favor of the cluster cohort containing the node with the lowest node number (i.e. Nodes 1,2 can talk to each other. The term "Split-Brain" is often used to describe the scenario when two or more co-operating processes in a distributed system, typically a high availability cluster, lose connectivity with one another but then continue to operate independently of each other, including acquiring logical or physical resources, under the incorrect assumption . Footnote2Rolling upgrades with Oracle Data Guard incur minimal downtime. The high availability benefits to using Oracle RAC One Node include the following: Offers better database availability than traditional cold failover solutions, Provides better virtualization for databases than hypervisor-based solutions, Enables online migration of database instances and online patching and upgrading of operating system and database software (incurring no downtime), Delivers a comprehensive, single-vendor solution, with no need to implement third-party products, Is ready to scale and upgrade to multinode Oracle RAC, Provides a standardized environment and a common toolset for both single-node and multinode Oracle database deployments, Is less expensive than cold fail over solutions or a full Oracle RAC deployment. Communication among the nodes is optimized by means of Redundant Interconnect Usage (without requiring the use of bonding or other technologies) to provide stability, reliability, and scalability. Also, to prevent a full cluster outage if either site fails, the configuration includes a third voting disk on an inexpensive, low-end standard network file system (NFS) mounted device. What is split brain in Oracle RAC? c. Some improvement has been made to ensure node(s) with lower load survive in case the eviction is caused by high system load. You can allocate server resources to multiple instances using Oracle Database Resource Manager Instance Caging. Consider using Oracle Database with Oracle GoldenGate if one or more of the following conditions are true: Updates are required on both sites or databases, and the changes must be propagated bidirectionally. The goal of the MAA is to remove the complexity in designing the optimal high availability architecture by providing configuration recommendations and tuning tips to optimize your architecture and Oracle features. If the sub-clusters are of the different sizes, the clusterware identifies the largest sub-cluster, and aborts all the nodes which do. Oracle Application Server provides redundancy by offering support for multiple instances supporting the same workload. For example, for a business that has a corporate campus, the extended Oracle RAC configuration could consist of individual Oracle RAC nodes located in separate buildings. For virtualization, Oracle RAC One Node with Oracle VM increases the benefit of Oracle VM with the high availability and scalability of Oracle RAC. Oracle Database with Oracle RAC architecture is designed primarily as a scalability and availability solution that resides in a single data center. Oracle RAC Split Brain Syndrome Scenerio. The group(cohort) with more cluster nodes survive Fast-Start Fault Recovery bounds and optimizes instance and database recovery times to minutes. Figure 7-3 Oracle Database with Oracle Clusterware (After Cold Cluster Failover). The figure shows Oracle Database with Oracle Data Guard architecture. The following list describes examples of Oracle Data Guard configurations using multiple standby databases: A world-recognized financial institution uses two remote physical standby databases for continuous data protection after failover. Online Application Maintenance and Upgrades with Edition-based redefinition allows an application's database objects to be changed without interrupting the application's availability. Footnote3Recovery time consists largely of the time it takes to restore the failed system. The fast-start failover has completed and the target standby database is running in the primary database role. Configurations and data must be synchronized regularly between the two sites to maintain homogeneity. Then, the redo data is applied from the logs to the physical standby database, which backs up the redo data to physical media. A logical copy configured and maintained using Oracle GoldenGate is called a replica, not a logical standby database, because it provides many capabilities that are beyond the scope of the normal definition of a standby database. You can configure Oracle GoldenGate with Oracle Data Guard to provide protection for the individual databases in the configuration. Dynamic Resource Provisioning allows for dynamic system changes. If the primary system should fail, the first standby database becomes the new primary database. However, the online changes are not supported by SQL Apply or data capture, and therefore the effects of this subprogram are not visible on the logical standby database or replica database. Table 7-3 identifies the additional capabilities provided by the architectures that build on Oracle Database and attempts to label each architecture with its greatest strengths. In this article I will explore this new feature for one of the possible factors contributing to the node weight, i.e. Provides seamless integration with, and migration to, Oracle Real Application Clusters (Oracle RAC) and Oracle Data Guard. Oracle Clusterware provides tolerance of node failures, whereas Oracle Data Guard provides additional protection against data corruptions, lost writes, and database and site failures. Similar to using Oracle Data Guard in SQL Apply mode, Oracle GoldenGate can capture database changes, propagate them to destinations, and apply the changes at these destinations. If the fast recovery area is on the source volume that is remotely mirrored, then you must also remotely mirror the flashback logs. which node first joined the cluster). Then there are two cohorts: {1, 2} and {3}. Footnote7Recovery time depends on block media recovery and the time it takes to restore a consistent block from the flashback logs or database backups, and to recover the block by applying all the redo from archive logs and online redo logs. For example, Table 7-1 provides some insight into the probability of different outages during unplanned and planned activities. As the result, 1 or more instance(s) will be evicted. Network addresses are failed over to the backup node. You might choose to use Oracle GoldenGate to configure and maintain a logical copy of your production database. When a database is started, Oracle Database allocates a memory area called the System Global Area (SGA) and starts one or more Oracle Database processes. The rightmost frame shows the configuration after fast-start failover has occurred. For an Oracle RAC database, each node in a cluster usually has one instance of the running Oracle software that references the database. The servers on which you want to run Oracle Clusterware must be running the same operating system. Site configurations are on heterogeneous platforms. If it takes seconds to detect a malicious DML or DLL transaction, it typically only requires seconds to flash back the appropriate transactions. 817202 Mar 1 2016 edited Mar 2 2016. For example: Active Data Guard, Redo Apply for physical standby databases, and SQL Apply for logical standby databases, multiple protection modes, push-button automated switchover and failover capabilities, automatic gap detection and resolution, GUI-driven management and monitoring framework, cascaded redo log destinations. host02 is retained as it has higher number of database services executing. The new primary database starts transmitting redo data to the new standby database. Run-time performance level management with Oracle Database Quality of Service Management (This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2)). If all the sub-clusters are of the same size, the sub-cluster having the lowest numbered node survives so that, in a 2-node cluster, the node with the lowest node number will survive. The script content on this page is for navigation purposes only and does not alter the content in any way. The following sections provide an overview of Oracle Database high availability architectures and implement the MAA best practices: Oracle Database with Oracle Clusterware (Cold Cluster Failover), Oracle Database with Oracle Real Application Clusters (Oracle RAC), Oracle Database with Oracle Clusterware and Oracle Data Guard, Oracle Database with Oracle RAC One Node and Oracle Data Guard, Oracle Database with Oracle RAC and Oracle Data Guard.

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