Introduction to the usage of RAC in Oracle

Usage of RAC in Oracle: 1. Provide high availability by running database instances on multiple servers; 2. Allow the number of nodes to be increased or reduced when needed; 3. By distributing the workload to multiple nodes to achieve load balancing; 4. Use shared storage to achieve data sharing between multiple nodes; 5. Allow multiple nodes to process database requests at the same time, thereby achieving parallel processing; 6. Provide a transparent failover function; 7. Use Provides some technologies to ensure data consistency; 8. Provides management tools to simplify the management and maintenance of RAC environment.

Oracle Real Application Clusters (RAC) is a feature of Oracle Database that allows a database instance to be run on multiple servers, which can share the same Physical storage. RAC provides high availability, scalability and load balancing solutions so that the database can better meet the needs of enterprises. In this article, we will introduce the usage of Oracle RAC and some of the key features it provides.

1. High availability: Oracle RAC provides high availability by running database instances on multiple servers. When one node fails, other nodes can take over its work, thus ensuring database continuity. RAC uses Oracle Clusterware to implement communication and coordination between nodes to ensure high availability of the database.

2. Scalability: Oracle RAC allows the number of nodes to be increased or reduced when needed, thereby achieving database scalability. By adding more nodes, the system's processing power and storage capacity can be increased to meet growing business needs. RAC also supports dynamic online node addition and deletion, and node expansion and reduction can be completed without downtime.

3. Load balancing: Oracle RAC achieves load balancing by distributing workloads to multiple nodes. RAC uses Oracle Clusterware to monitor the load of nodes and automatically allocate workloads to the most suitable nodes based on the load. This can improve the performance and throughput of the system and avoid the performance bottleneck of a single node.

4. Shared storage: Oracle RAC uses shared storage to achieve data sharing between multiple nodes. Shared storage can be SAN (Storage Area Network) or NAS (Network Attached Storage). Multiple nodes can access data files and log files in shared storage at the same time, thereby achieving data consistency and reliability.

5. Parallel processing: Oracle RAC allows multiple nodes to process database requests at the same time, thereby achieving parallel processing. This can improve the system's processing power and response speed, especially when handling a large number of concurrent requests. RAC uses Oracle Parallel Server (OPS) technology to implement parallel processing between nodes.

6. Transparent failover: Oracle RAC provides a transparent failover (Transparent Failover) function. When a node fails, RAC can automatically switch the workload to other nodes without requiring manual intervention by the user. . This minimizes system downtime and risk of data loss.

7. Data consistency: Oracle RAC uses some technologies to ensure data consistency. For example, it uses Cache Fusion technology to share data blocks between nodes to ensure data consistency. In addition, RAC also provides some mechanisms to handle concurrent access and update conflicts to avoid data inconsistency.

8. Management tools: Oracle RAC provides some management tools to simplify the management and maintenance of the RAC environment. For example, Oracle Enterprise Manager (OEM) provides a graphical interface that can be used to monitor and manage RAC environments. In addition, there are command line tools and scripts that can be used to perform common management tasks such as node addition, removal, and failover.

Summary

Oracle RAC is a powerful database feature that provides high availability, scalability and load balancing solutions. By running database instances on multiple servers and using shared storage to share data, RAC can improve the performance, availability, and scalability of the system. In addition, RAC also provides some management tools to simplify the management and maintenance of RAC environment. Oracle RAC is a valuable choice for enterprises requiring high availability and performance.

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