High Availability (HA) and RAC New Features in 11g Oracle 11g New Features Tips by Burleson Consulting July 8, 2008

Oracle 11g SQL New Features Tips

Background of Oracle RAC

Adoption of high availability practices are quickly becoming one of the hottest trends in the Oracle field.  As data becomes more and more crucial to millions of businesses worldwide, it is being found that enterprise business cannot tolerate downtime.

Thanks to advances in Business Intelligence (BI), many companies now employ vast networks of decision support systems, expert systems, and analytic databases to back their OLTP environments.  These warehouses, which once could be taken offline for days at a time, are now expected to remain online with the same uptime as one would expect from an enterprise public-facing environment.  In short, data rules the business world.

Unfortunately, servers, databases, and applications can go offline for a variety of reasons.  Sometimes downtime is expected such as in the case of a planned outage for upgrades.  Still more dangerous is unplanned downtime, such as when a component failure causes an outage, or worse, data loss.

Oracle has made great strides to keep enterprise systems online and operational at all times.  Perhaps the largest advances came in Oracle 9i, when Oracle introduced Real Application Clusters (RAC) to replace Oracle Parallel Server (OPS).  This move allowed more clients to take on a clustered Oracle environment without sacrificing performance and manageability.  RAC allowed not only a better scalability model across multiple clustered nodes, but a transparent application layer, allowing any applications to connect to a RAC cluster without any extra consideration on the part of the application developer.

Oracle 10g enhanced the RAC product, introducing portable Oracle-driven Clusterware, new administrative tools, and performance enhancements.  These new changes transformed the look of RAC to include such concepts as Virtual IPs (VIPs) and the Oracle Notification Server (ONS).  Another important feature known as “services” were introduced, allowing a Remote DBA to manage and use RAC connections while leaving a simple connection method for applications.  These services allowed a Remote DBA to manage resource use such as CPU and parallel processes on each node across the cluster, while also providing failover capabilities using Transparent Application Failover (TAF) on the backend.

Oracle 11g extends the 10g RAC framework with new features targeted towards providing optimal throughput while retaining total uptime.  In addition, Oracle has expanded products such as Dataguard to provide additional fault prevention. All of this together forms the Maximum Availability Architecture (MAA).  The MAA is an Oracle model for high uptime and complete disaster recovery.  In this chapter, how Oracle 11g makes high availability a scalable, high performance, enterprise-ready model will be explored.

Scalability

Oracle RAC truly shines as a high availability solution, but it also allows a certain degree of scalability.  Traditional monolithic computing architecture has always endorsed vertical scalability as the means to grow an enterprise.  Therefore, when a business function has outgrown its server, more RAM, CPU, and disk resources could be added to the server to make it more powerful.  When the server reached capacity, a new monolithic powerhouse would be required.

Now, with RAC, companies are able to grow their database environment horizontally.  This means that instead of building their database hardware up, they expand out into multiple servers.  Oracle RAC allows connections to all servers in a cluster simultaneously.  Oracle 11g expands on this concept and allows more intelligent load balancing in order to improve scalability.  In this section, these new scalability enhancements will be reviewed along with some 10g capabilities, most of which fall under the title of Automatic Workload Management (AWM).

 

This is an excerpt from the new book Oracle 11g New Features: Expert Guide to the Important New Features by John Garmany, Steve Karam, Lutz Hartmann, V. J. Jain, Brian Carr. You can buy it direct from the publisher for 30% off.