I will explain Architecture of Oracle RAC ( Real Application Cluster ) and What is the Oracle RAC in this article
In order to provide High Availability for Oracle database, Real Application Cluster (RAC) software was introduced in 2001 together with Oracle 9i.
You have the possibility of running the databases as Cluster on multiple nodes against possible server corruption with the Oracle RAC Technology. Thus, a single database can be run with multiple Instances on multiple servers.
The features of Real Application Cluster are as follows.
- High Availability: Production database provides a service uptime up to 99.99%.
- Server ( Machine ) Redundancy: When a database is running on more than one server as cluster, any node or server fails or power off undesirably, Database continue to run from the other node or nodes without downtime.
- Load balancing: You can create database service and run different services on different nodes in this way.
Our databases are running on a server or machine and these servers can be broken because of Following errors.
- MotherBoard failures
- Disk failures
- Server failures
- Memory, RAM failures
- CPU failures
- Power supply failures
If There are faults in the server like above , and Applications have downtime because of database in the Bank, Insurance, Public, Hospital, etc. in critical institutions, then these excuses are not accepted by customers.
To solve or prevent this crisis, we need to set up Oracle Database Cluster, that is Real application cluster.
The overall architecture of Oracle Real Application Cluster is as follows.
The requirements for the RAC Installation are as follows.
1- Two or More Servers: They can be both Physical server and Virtual machine. It is recommended using Linux or Unix instead of Windows for the Oracle RAC installation. I have installed Oracle RAC on Linux, so You can install Oracle linux 7.6 with this link.
2- Shared Storage: Shared disks must be provided to the both nodes or servers and all nodes need to access shared storage synchronously. Common database files ( datafiles,controlfiles,archivelogs,onlinelogs,spfile) will be kept on this storage.
3- Private Network: Private IPs and network need to provide for both servers to perform Interconnect or heartbeat.
Servers will always communicate with each other via this network.
4- Public Network: 2 Public hostname IPs, 2 VIPs and 3 SCAN IPs are need to be provided for installation.
I will explain Oracle RAC installation in the Next article.