Node 2 is connected to Node 1 and to Oracle Database, but it is currently standby mode. Also, you can use the Oracle Clusterware ability to relocate applications and application resources (using the crsctl relocate resource command) as a way to move the workload to another node so that you can perform planned system maintenance on the production server. Oracle recommends that you use automatic undo management with sufficient space to attain your desired undo retention guarantee, enable Oracle Flashback Database, and allocate sufficient space and I/O bandwidth in the fast recovery area. 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. 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. A highly available application must analyze every component that affects the application, including the network topology, application server, application flow and design, systems, and the database configuration and architecture. The group(cohort) with more cluster nodes survive RAC Split Brain Syndrome. Their strategy further mitigates risk by maintaining multiple standby databases, each implemented using a different architecturesRedo Apply and SQL Apply. Any database in a Data Guard configuration, whether a primary or standby database, can be an Oracle One Node database. Oracle Clusterware provides a number of benefits over third-party clusterware. Fully supports Oracle Data Guard. In previous releases, technologies like bonding or trunking were used to make use of redundant networks for the interconnect. Figure 7-7 shows the production database at the primary site and multiple standby databases at secondary sites. pagespeed.lazyLoadImages.overrideAttributeFunctions(); So, in a two node situation both the instances will think that the other instance is down because of lack of connection. 2. All Oracle RAC nodes can be active by implementing multiple Oracle RAC One Node configurations for different databases. Rolling upgrade for system, clusterware, database, and operating system. Split Brain Syndrome: In a Oracle RAC environment all the instances/servers communicate with each other using high-speed interconnects on the private network. Oracle Quality of Service (QoS) Management for policy-based run-time management of resource allocation to database workloads to ensure service levels are met in order of business need under dynamic conditions. Footnote4Database is still available, but a portion of the application connected to the failed system is temporarily affected. Site configurations are on heterogeneous platforms. We will verify that when an unequal number of database services are running on the two nodes, the node hosting the higher number of database services survives even if it has a higher node number. 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 node running your Oracle RAC One Node becomes overloaded, you can relocate the instance to another node in the cluster using the online database relocation utility (srvctl relocate database), with no downtime for application users. In Oracle Database 11g Release 2 (11.2), Oracle RAC One Node or Oracle RAC is the preferred solution over Oracle Clusterware (Cold Cluster Failover) because it is a more complete and feature-rich solution. Because Oracle Data Guard only propagates the redo data in the logs, and the log file consistency is checked before it is applied, all such external corruptions are eliminated by Oracle Data Guard. In this article I will explore this new feature for one of the possible factors contributing to the node weight, i.e. In simpler terms, in a split-brain situation, there are in a sense two (or more) separate clusters working on the same shared storage. When the two data centers are located relatively close to each other, extended clusters can provide great protection for some disasters, but not all. Maximum RTO for data corruption, cluster, database, or site failures is in seconds to minutes. Provides maximum protection from physical corruptions. 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. 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 . The script content on this page is for navigation purposes only and does not alter the content in any way. Nodes 1,2 can talk to each other. Oracle RAC allows multiple computers to run Oracle RDBMS software simultaneously while accessing a single database, thus providing clustering. You should adopt the MAA best practices to achieve the optimal recovery time and configuration. Data Recovery Advisor provides intelligent advice and repair of different data failures, Oracle Secure Backup provides a centralized tape backup management solution. However, remote mirroring solutions affect DBWR process performance because they subject all DBWR process write I/O's to network and disk I/O induced delays inherent to synchronous, zero-data-loss configurations. The figure shows the same Oracle Data Guard configuration in three different frames, as described in the following list: The leftmost frame shows the configuration before fast-start failover occurs. (For complete disaster recovery and data protection, use the architecture shown in Figure 7-8.). Figure 7-5 shows an Oracle RAC extended cluster for a configuration that has multiple active instances on six nodes at two different locations: three nodes at Site A and three at Site B. Flexible and automated high availability solutions ensure that applications you deploy on Oracle Application Server meet the required availability to achieve your business goals. A world-recognized e-commerce site uses multiple standby databasesa mix of both physical and logical databasesboth for disaster recovery and to scale out read performance by provisioning multiple logical standby databases using SQL Apply. Corruption Prevention, Detection, and Repair detect and prevent some corruptions and lost writes. The new primary database starts transmitting redo data to the new standby database. Maximum RTO for instance or node failure is in seconds to minutes. If the fast recovery area is on the source volume that is remotely mirrored, then you must also remotely mirror the flashback logs. It requires only a standard TCP/IP-based network link between the two computers. the number of database services executing on a node. To avoid splitbrain, node 2 aborted itself. Oracle Database with Oracle RAC on Extended Clusters. As per Split brain syndrome in Oracle RAC in case of inter-connect failures the master node will evict other/dead nodes . At the time of role transition, more storage and system resources can be allocated toward that application. Higher flexibilityOracle Data Guard is implemented on pure commodity hardware. Clients are connected to the logical standby database and can work with its data. This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2). You might choose to use Oracle GoldenGate to configure and maintain a logical copy of your production database. 2. Provides seamless integration with, and migration to, Oracle Real Application Clusters (Oracle RAC) and Oracle Data Guard. Online Patching allows for dynamic database patches for diagnostic and interim patches. Fast-start failover is recommended to provide automatic failover without user intervention and bounded recovery time. The public and private interconnects, and the Storage Area Network (SAN) are all on separate dedicated channels, with each one configured redundantly. The following list describes examples of Oracle Data Guard configurations using single standby databases: A national energy company uses a standby database located in a separate facility 10 miles away from its primary data center. Node 1 is connected to Node 2 and to the Oracle database, but Node 1 is currently idle, in standby mode. Maximum RTO for instance or node failure is zero for the databaseFootref1. But 1 and 2 cannot talk to 3, and vice versa. 2. Oracle recommends that you create and store the local backups in the fast recovery area. c. Some improvement has been made to ensure node(s) with lower load survive in case the eviction is caused by high system load. Let say 2 node RAC configuration node 1 is defined as master node (by some parameter like load and others) incase of network failures node 1 will terminate node 2 . Figure 7-3 Oracle Database with Oracle Clusterware (After Cold Cluster Failover). However, an extended cluster cannot protect against all data corruptions or specific data failures that impact the database, or against comprehensive disasters such as earthquakes, hurricanes, and regional floods that affect a greater geographical area. Whatever the case, these Oracle RAC interview questions and answers are for you. This book focuses primarily on the database high availability solutions. Oblivious of the existence of other cluster fragments, each sub-cluster continues to operate independently of the others. which node first joined the cluster). This architecture is identical to the single-standby database architecture that was described in Section 7.1.5.1, except that there are multiple standby databases in the same Oracle Data Guard configuration. The individual nodes are running fine and can accept user connections and work . At the logical standby database, the redo data is transformed into SQL statements, which are applied to the logical standby database. Oracle Flashback Technology optimizes logical failure repair. Online Reorganization and Redefinition allows for dynamic data changes. Although traditional solutions (such as backup and recovery from tape, storage-based remote mirroring, and database log shipping) can deliver some level of high availability, Oracle Data Guard provides the most comprehensive high availability and disaster recovery solution for Oracle databases. Flexible propagation and management of data, transactions, and events. You can configure Oracle GoldenGate with Oracle Data Guard to provide protection for the individual databases in the configuration. With Database Server Grid and Database Storage Grid (described in Section 5.2 and Section 5.3), you can build standby database and testing hubs that use a pool of system resources. Oracle RAC Split Brain Syndrome Scenerio. 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. It allows you to select the table columns depending on a set of criteria. During the process of resolving conflicts, information may be lost or become corrupted.
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