Limited support for mixed platforms. However, when you use Oracle Clusterware, there is no need or advantage to using third-party clusterware. In Oracle RAC, all the instances/servers communicate with each other using a private network. However, if a remote mirroring solution is used for data protection, typically you must mirror the database files, the online redo log, the archived redo logs, and the control file. Common messages in instance alert log are similar to: In above example, instance 2 LMD0 (pid 29940) is the receiver in IPC Send timeout. Footnote3Recovery time consists largely of the time it takes to restore the failed system. Oracle Data Guard provides a number of advantages over traditional solutions, including the following: Fast, automatic or automated database failover for data corruptions, lost writes, and database and site failures, Automatic corruption repair automatically replaces a corrupted block on the primary or physical standby by copying a good block from a physical standby or primary database, Most comprehensive protection against data corruptions and lost writes on the primary database, Reduced downtime for storage, Oracle ASM, Oracle RAC, system migrations and some platform migrations, and changes using Data Guard switchover, Reduced downtime with Oracle Data Guard rolling upgrade capabilities, Ability to off-load primary database activitiessuch as backups, queries, or reportingwithout sacrificing the RTO and RPO ability to use the standby database as a read-only resource using the real-time query apply lag capability, Ability to integrate non-database files using Oracle Database File System (DBFS) as part of the full site failover operations, No need for instance restart, storage remastering, or application reconnections after site failures, Transparent and integrated support for application failover. You can allocate server resources to multiple instances using Oracle Database Resource Manager Instance Caging. Support for heterogeneous platforms, versions, and character sets. In Oracle RAC, all the instances/servers communicate with each other using a private network. This architecture is the recommended configuration for Maximum Availability Architecture (MAA). Also, see Figure 5-2 for another example of a multiple standby database environment. Oracle Flashback Technology optimizes logical failure repair. The following list describes some implementations for a multiple standby database architecture: Continuous and transparent disaster or high availability protection if an outage occurs at the primary database or the targeted standby database, Regional reporting or reader databases for better response time, Synchronous redo transport that transmits to a more local standby database, and asynchronous redo transport that transmits to a more remote standby database for optimum levels of performance and data protection, Transient logical standby databases (described in Section 3.6.3) for minimal downtime rolling upgrades, Test and development clones using snapshot standby databases (described in Section 3.6.4), Scaling the configuration by creating additional logical standby databases or snapshot standby databases. For data resident in Oracle databases, Oracle Data Guard, with its built-in zero-data-loss capability, is more efficient, less expensive, and better optimized for data protection and disaster recovery than traditional remote mirroring solutions. Network connection changes and other site-specific failover activities may lengthen overall recovery time. Oracle Database with Oracle RAC on Extended Clusters. Any database in a Data Guard configuration, whether a primary or standby database, can be an Oracle One Node database. After you have chosen an architecture, then implement it using the operational and configuration best practices described in the MAA white papers and in Oracle Database High Availability Best Practices. b. Then, the redo data is applied from the logs to the physical standby database, which backs up the redo data to physical media. 2. What is Voting Disk & Split Brain Syndrome in RAC Clients are connected to the logical standby database and can work with its data. Oracle Application Server provides high availability and disaster recovery solutions for maximum protection against any kind of failure with flexible installation, deployment, and security options. Provides the simplicity of a physical replica. The observer (thin client watchdog) resides in the application tier and monitors the availability of the primary database. 817202 Mar 1 2016 edited Mar 2 2016. The database consists of a collection of data files, control files, and redo logs located on disk. Voting disk is used by Oracle Cluster Synchronization Services Daemon (ocssd) on each node, to mark its own attendance and also to record the nodes it can communicate with. The sum of benefits of Oracle Clusterware with Oracle Data Guard, Best high availability, data protection, and disaster-recovery solution with scalability built in, The sum of benefits of Oracle RAC with Oracle Data Guard, Oracle Database with Oracle GoldenGateFoot3, Bidirectional replication and information management, Replica database (or databases) available for read/write use, Fast failover for computer failure and storage failure, Minimum downtime for computer or site maintenance and database and application upgrades. Top 25 Oracle RAC Interview Questions and Answers in 2023 In a typical example, the maximum distance between the systems connected in a point-to-point fashion and running synchronously can be only 10 kilometers. Oblivious of the existence of other cluster fragments, each sub-cluster continues to operate independently of the others. For example, if the extended cluster configuration is set up properly, it can protect against disasters such as a local power outage, an airplane crash, or a flooded server room. For more information, see "Data Guard Support for Heterogeneous Primary and Physical Standbys in Same Data Guard Configuration" in My Oracle Support Note at, https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=413484.1. Maximum RTO for data corruptions, database, or site failures is in seconds to minutes. In such a scenario, integrity of the cluster and its data might be compromised due to uncoordinated writes to shared data by independently operating nodes. Since I will only explore the scenarios for which functionality has been modified, i.e. Footnote2Oracle ASM automatically rebalances stored data when disks are added or removed while the database remains online. Oracle Secure Backup provides a centralized tape backup management solution. Maximum RTO for instance or node failure is zero for the databaseFootref1. The configuration can be an active-active configuration using Oracle Application Server Cluster or an active-passive configuration using Oracle Application Server Cold Cluster Failover. Disaster strikes the primary database, and its network connections to both the observer and the target standby database are lost. 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 operate independently of each other. Oracle Database with Oracle GoldenGate provides granularity and control over what is replicated and how it is replicated. Applications can easily mask failures to the end user. Split Brain Syndrome, In a Oracle RAC environment all the instances/servers communicate with each other using high-speed interconnects on the private network. The group(cohort) with more cluster nodes survive Oracle Data Guard Advantages Over Traditional Solutions. It also allows the storage to be laid out in a different fashion from the primary computer. If your VM is sized too small, you can migrate the Oracle RAC One instance to another larger Oracle VM node in the cluster (using the online database relocation utility) or move the Oracle RAC One instance to another Oracle VM node, and then resize the Oracle VM. If the primary database uses the asynchronous redo transport, configure your maximum data loss tolerance or the Oracle Data Guard broker's FastStartFailoverLagLimit property to meet your business requirements. Split Brain Syndrome in RAC. Start both the services for database admindb so that serv1 executes on host01 and serv2 executes on host02. PDF Oracle Clusterware 12c Release 2 Technical Overview For high availability, Oracle recommends that you have a minimum of three voting disks. Then this process is referred as Split Brain Syndrome. Table 7-5 compares the attainable recovery times of each Oracle high availability architecture for all types of planned downtime. With Oracle Clusterware, you can provide a cold cluster failover to protect an Oracle Database instance from a system or server failure. host01 is retained as it has a lower node number. Both the primary and secondary sites contain Oracle Application Servers, two database instances, and an Oracle database. The second standby database automatically receives data from the new primary database, insuring that data is protected at all times. 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)), Zero downtime with Grid Control provisioning, Rolling upgrade for system, clusterware, operating system, CPUs, and some Oracle interim patchesFoot1, Database Grid with site failure protection, Simplest high availability, data protection, and disaster-recovery solution, Automatic and fast failover for computer failure, storage failure, data corruption, for configured ORA- errors or conditions and database failures, Rolling upgrade for system, clusterware, database, and operating systemFoot2, Ability to off-load backups to the standby database, Ability to off-load read and reporting workload to the standby database. 008 - How Node Membership Happens in RAC? - What is Voting Disk & Split 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 . Higher ROIBusinesses must obtain maximum value from their IT investments, and ensure that no IT infrastructure is sitting idle. Figure 7-2 Oracle Database with Oracle Clusterware (Before Cold Cluster Failover). Split brain syndrome occurs when the instances in a RAC fails to connect or ping to each other via the private interconnect. Oracle Data Guard Advantages Compared to Remote Mirroring Solutions. Oracle Real Application Cluster (RAC) is a unique technology that offers software for high availability and clustering in an Oracle database environment. Oracle RAC One Node provides relocation of Oracle RAC primary and standby databases configured with Oracle Data Guard (This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2)). Oracle Data Guard provides more comprehensive data protection and its more efficient network usage allows plenty of room to grow without the expense of upgrading its network. The individual nodes are running fine and can accept user connections and work . However, starting from Oracle Database 12.1.0.2c, the node with higher weight will survive during split brain resolution. (For complete disaster recovery and data protection, use the architecture shown in Figure 7-8.). In Oracle RAC each node in the cluster is interconnected through a private interconnect. Oracle Clusterware manages the availability of both the user applications and Oracle databases. So, in a two node situation both the instances will think that the other instance is down because of lack of connection. Furthermore, operational practices across role transitions are simplified when the sites are symmetric. Footnote1Architectures for which the MO is high might require additional time and expertise to build and maintain, but offer increased flexibility and capabilities required to meet specific business requirements. Oracle RAC on an extended cluster provides greater availability than a local Oracle RAC cluster, but an extended cluster may not completely fulfill the disaster recovery requirements of your organization.
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