High Availability (HA) and RAC New Features in
Oracle 11g New Features Tips by Burleson
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
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.
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.
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