What is the Oracle RAC and Architecture of Real Application Cluster


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. Related link is as follows.


Oracle RAC Step by Step Installation on Linux -1



Do you want to learn Oracle Database for Beginners, then read the following articles.


About Mehmet Salih Deveci

I am Founder of SysDBASoft IT and IT Tutorial and Certified Expert about Oracle & SQL Server database, Goldengate, Exadata Machine, Oracle Database Appliance administrator with 10+years experience.I have OCA, OCP, OCE RAC Expert Certificates I have worked 100+ Banking, Insurance, Finance, Telco and etc. clients as a Consultant, Insource or Outsource.I have done 200+ Operations in this clients such as Exadata Installation & PoC & Migration & Upgrade, Oracle & SQL Server Database Upgrade, Oracle RAC Installation, SQL Server AlwaysOn Installation, Database Migration, Disaster Recovery, Backup Restore, Performance Tuning, Periodic Healthchecks.I have done 2000+ Table replication with Goldengate or SQL Server Replication tool for DWH Databases in many clients.If you need Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS Consultancy and Training you can send my email adress [email protected].-                                                                                                                                                                                                                                                 -Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  [email protected] a mail atabilirsiniz.


  1. simple and good explanation..

  2. Your profile is very much appreciative Sir.I am also a DBA and I try to learn more and more everyday.

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