Figure 7-8 shows an Oracle Clusterware and Oracle Data Guard architecture that consists of a primary and a secondary site. Node 2 is connected to Node 1 and to Oracle Database, but it is currently standby mode. In a "split brain" situation, voting disk is used to determine which node (s) will survive and which node (s) will be evicted. b. Applications scale in an Oracle RAC environment to meet increasing data processing demands without changing the application code. This private network interface or interconnect are redundant and are only used for inter-instance oracle data block transfers. Support for bidirectional replication and updating anything and anywhere. Vijay.Cherukuri-Oracle Dec 18 2011 edited Nov 5 2012. See the high availability solutions and recommendations for Oracle Application Server, Oracle Enterprise Manager, and Oracle Applications on the MAA Web site at: Oracle Database High Availability Best Practices, Oracle Real Application Clusters Administration and Deployment Guide, Oracle Data Guard Concepts and Administration, Oracle Streams Replication Administrator's Guide, Oracle Fusion Middleware High Availability Guide, Oracle Application Server High Availability Guide, Section 1.5, "Roadmap to Implementing the Maximum Availability Architecture (MAA)", Corruption Prevention, Detection, and Repair, Online Application Maintenance and Upgrades, Description of "Figure 7-1 Single-Node, Nonclustered Oracle Database with an Oracle ASM Instance", Section 7.1.3, "Oracle Database with Oracle RAC One Node", Description of "Figure 7-2 Oracle Database with Oracle Clusterware (Before Cold Cluster Failover)", Description of "Figure 7-3 Oracle Database with Oracle Clusterware (After Cold Cluster Failover)", Description of "Figure 7-4 Oracle Database with Oracle RAC Architecture", Description of "Figure 7-5 Oracle RAC Extended Cluster", http://www.oracle.com/technetwork/database/clustering/overview/, Description of "Figure 7-6 Primary and Standby Databases and the Observer During Fast-Start Failover", Description of "Figure 7-7 Oracle Database with Oracle Data Guard on Primary and Multiple Standby Sites", Description of "Figure 7-8 Oracle Clusterware (Cold Cluster Failover) and Oracle Data Guard", Description of "Figure 7-9 Oracle Database with Oracle RAC and Oracle Data Guard - MAA". The production database transmits redo data (either synchronously or asynchronously) to redo log files at the physical standby database. Maximum RTO for instance or node failure is in minutes. This section summarizes the advantages of the different high availability architectures and provides guidelines for you to choose the correct high availability architecture for your business. Section 3.4.1 describes how Oracle Clusterware is software that, when installed on servers running the same operating system, enables the servers to be bound together to operate as if they are one server, and manages the availability of user applications and Oracle databases. Following the execution of a SELECT statement, a tabular result is held in a result table (called a result set). Oracle Flashback Technology optimizes logical failure repair. They will enhance your knowledge and help you to emerge as the best candidate. In the figure, Node 2 is now the active instance connected to the Oracle database and servicing applications and users. Oracle Enterprise Management support for Oracle ASM and Oracle ACFS, Grid Plug and Play, Cluster Resource Management, Oracle Clusterware and Oracle RAC Provisioning and patching, Figure 7-4 shows Oracle Database with Oracle RAC architecture. When a node is physically up and running and database instances are also running fine, but private interconnect fails between two or more nodes and an instance member fails to connect or ping to one . If it takes seconds to detect a malicious DML or DLL transaction, it typically only requires seconds to flash back the appropriate transactions. The split brain syndrome and its affects and how it has been managed in oracle is mentioned below. The common voting result will be: a. However, starting from Oracle Database 12.1.0.2c, the node with higher weight will survive during split brain resolution. Recovery Manager (RMAN) optimizes local repair of data failures. Fast-Start Fault Recovery bounds and optimizes instance and database recovery times to minutes. End-users connect to clusters through a public network. In this article I will explore this new feature for one of the possible factors contributing to the node weight, i.e. Why is it like that? This chapter describes the various high availability architectures in an Oracle environment and helps you to choose the correct architecture for your organization. For example, if the primary database fails over to one of the standby databases in the Data Guard hub, the new primary database acquires more system and storage resources while the testing resources may be temporarily starved. 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. The probability of failing over all databases at the same time is unlikely. All Oracle RAC nodes can be active by implementing multiple Oracle RAC One Node configurations for different databases. 1. You can achieve the highest level of availability when using Oracle RAC and Oracle Data Guard and there is no need to make application changes to use these Oracle Database features. Filed Under: oracle, RAC Tagged With: RAC, split brain, vcs basics Communication faults, jeopardy, split brain, I/O fencing, How to Enable or Disable Veritas ODM for Oracle database 12.1.0.1, ORA-16713: The Oracle Data Guard broker command timed out When Changing LogXptMode, Managing Oracle Database Backup with RMAN (Examples included), Cron Script does not Execute as Expected from crontab Troubleshoot, Oracle SQL Script to Report Tablespace Free and Fragmentation, Beginners Guide to Flash Recovery Area in Oracle Database, How to Identify the Last and Next Refresh Dates for a Materialized View, Oracle 20c New Feature: PDB Point-in-Time Recovery or Flashback to Any Time, How to use nomodeset to Troubleshoot Boot Issues. Oracle Data Guard is designed to allow businesses get something useful out of their expensive investment in a disaster-recovery site. The problem which could arise out of this situation is that the sane . Split Brain is often used to describe the scenario when two or more nodes in a 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 that the other process (es) are no longer operational or . This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2). Uses a private network and voting disk-based communication to detect and resolve split-brainFoot2 scenarios. Choice of RPO equal to zero (SYNC) or near-zero (ASYNC). For physical standby databases, this solution: Supports very high primary database throughput. The figure shows users making local updates to the snapshot standby database. In a split brain situation, voting disk will be used to determine which node(s) survive and which node(s) will be evicted. Oracle Flashback Technology optimizes logical failure repair. The recommended high availability and disaster-recovery architectures that use Oracle Data Guard are described in the following sections: Overview of Single Standby Database Architectures, Overview of Multiple Standby Database Architectures. Whatever the case, these Oracle RAC interview questions and answers are for you. Footnote4Tables can be reorganized online using the DBMS_REDEFINITION package. After the former primary database has been repaired, the observer reestablishes its connection to that database and reinstates it as a new standby database. FAN with integrated Oracle client failover, including Java applications using UCP with Oracle RAC and Oracle Data Guard. Oracle Database with Oracle RAC architecture is designed primarily as a scalability and availability solution that resides in a single data center. There is no fancy or expensive hardware required. Uses a private network and voting disk-based communication to detect and resolve split-brain Foot 2 scenarios. Now talking about split-brain concept with respect to oracle RAC systems, it occurs when the instance Split Brain Condition occurs when a single cluster has a failure that results in reconfiguration of cluster into multiple partitions, with each partition forming its own sub-cluster without the knowledge of the existence of other. host01 is retained as it has a lower node number. Start both the services for database admindb so that equal number of database services execute on both the nodes. With Oracle RAC integration, database scalability is possible. Then this process is referred as Split Brain Syndrome. Unlike the cold cluster model where one node is completely idle, all instances and nodes can be active to scale your application. 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. Oracle Database is a single-instance, standalone (noncluster) database and it is the foundation for all high availability architectures. Figure 7-6 shows the relationships between the primary database, target standby database, and the observer before, during, and after a fast-start failover. Maximum RTO for instance or node failure is in seconds to minutes. Oracle RAC allows multiple computers to run Oracle RDBMS software simultaneously while accessing a single database, thus providing clustering. Note, however, that the synchronous redo transport does not impose any physical distance limitation. The combination of Oracle RAC and Oracle Data Guard provide the most comprehensive architecture for reducing downtime for scheduled outages and preventing, detecting, and recovering from unscheduled outages. Online Patching allows for dynamic database patches for diagnostic and interim patches.