Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 









Oracle Data Warehouses in a RAC Environment

Oracle Database Tips by Donald Burleson

2014 Update:  Please see these 2015 updates to Oracle hardware architectures and the costs and benefits of server deconsolidation.

While Oracle Real Application Clusters (RAC) is not the ideal hardware architecture for Oracle data warehouse applications, some shops require the robust features of RAC for their data warehouse applications.

Generally, only shops that need 100% continuous availability or fast scalability choose RAC for a data warehouse, primarily because of the huge licensing costs and human effort required for proper installation and configuration.

Oracle RAC is not the best solution to data warehouse applications because they require large banks of CPU's to perform parallel table-scan operations.  Mike Ault, noted Oracle data warehouse consultant notes "I have never heard of any shop using RAC for a data warehouse, and I could imaging large parallel operations clobbering the interconnect as to make RAC somewhat sub-optimal for data warehouse processing".

Unlike a monolithic data server where CPU and RAM resources are allocated automatically, Oracle RAC systems must have manual load balancing mechanisms to distribute the load across the server blades.

The costs of RAC

Oracle RAC is expensive to purchase and even more expensive to configure, especially in a data warehouse environment.  It is not uncommon to spend weeks of DBA effort allocating data warehouse ETL and aggregation jobs to minimize the impact and load balance between the server blades. 

Transparent Application Failover Configuration

We have many choices for RAC failover, each with differing complexity and overhead, depending on the needs of the COHORT users.  My article from Oracle Magazine, explains these issues:

Parallel Query in RAC

Especially challenging will be the parallel parallelism that is required to implement super-fast rollups in a massively-parallel environment, a task that can take a week or more to test and configure.

RAC load balancing

We also have to manage load-balancing for RAC, and this involves extensive manual configuration to use a round-robin configuration to distribute the load among the instances.  Starting in Oracle 10g release 2, we have a brand-new load-balancing advisory that promises to cut-down the manual effort for RAC load balancing between instances:


Time estimates for RAC configuration

It is highly recommended that COHORT utilize Oracle 10g release 2 RAC because of the improved RAC load-balancing automation which can save thousands of dollars,  Here are time estimates for a seasoned Oracle RAC DBA Consultant (with experience installing RAC on dozens of environments) for a typical RAC install and configuration.  A certified DBA without experience may take double these numbers:

TASK                                  Hours    
Review hardware components              8
Install cluster components             24
Test and configure RAC servers          8
Configure TAF                          15
Configure Oracle parallel query         9
Configure automatic load-balancing     16
Approximate Total Time                                     80 hours
Because an experienced  Oracle RAC consultant is more productive, many corporations outsource the RAC installation and configuration to Oracle consultancies such as Burleson Consulting..

Oracle Grid and Real Application Clusters

See working examples of Oracle Grid and RAC in the book Oracle Grid and Real Application Clusters.

Order directly from Rampant and save 30%. 



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster


Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2020

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.