||Oracle Tips by Burleson
Oracle10g Grid Computing
Chapter 3 - High
Performance and Highly Available
It does suffer from some drawbacks as well:
More coordination is required.
More overhead is required in terms of
processing or function shipping for a SQL operation working on a
data/disk belonging to another node.
Data skew is a potential problem. As data
is added to the database and access patterns change, data
re-partition is needed to balance IO.
In the Shared-Disk model, all the disks
containing data are accessible by all nodes of the cluster. Disk
sharing architecture requires suitable lock management techniques to
control the update concurrency control. Each of the nodes in the
cluster has direct access to all disks on which shared data is
placed. Fig. 3.11 shows typical three node parallel database
cluster. Each node has local database buffer cache. IBM Parallel
Sysplex and Oracle RAC systems follow this approach of shared-disk.
Advantages of shared disk systems are as
Shared disk systems permit high
availability. All data is accessible even if one node fails.
These systems have the concept of “One
Database” and multiple access points. In other words, we can say
it is “multi-instance and single database”. There is no issue
such as data skew as the data is located and accessed at a
It provides for incremental growth of nodes
and thus adds to processing power.
Figure 3.11 Shared Disk Parallel Database Cluster
For more information,
see the book
Grid and Real Application Clusters 30% off if you
buy it directly from Rampant TechPress .
Written by top Oracle
experts, this RAC book has a complete online code depot with
ready to use RAC scripts.
Oracle Consulting Services
Burleson Oracle Consulting offers Senior Oracle consultants which are available
for all areas of Oracle support. Common Oracle consulting support
activities include short-term Oracle tuning, Oracle database troubleshooting,
Oracle9i and Oracle10g migration,
Oracle9iAS App Server
consulting, Oracle design reviews and
Oracle requirements evaluation support. Oracle support and Oracle consulting
services are priced by the hour, so you only pay for what you need. These
one-time Oracle consulting services commonly include:
Answering questions from your Oracle DBA technical staff
Repairing down production Oracle database systems
One-time Oracle tuning evaluation
Guru support for your Oracle DBA
Installation of Oracle application packages
For more information, please visit