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Oracle SCAN and converting from a single entry SCAN to DNS SCAN

Oracle SCAN and converting from a single entry SCAN to DNS SCAN

In the article you will have a look at the steps to modify SCAN configuration while converting your SCAN from a single entry residing in /etc/hosts to a SCAN based on 3 DNS entries. SCAN was introduced in 11.2 and allows a single name to be used for the clients to connect to the RAC cluster. SCAN load balances across the node listeners to connect to the instance that provides the best quality of service for a service. SCAN provides a transparency of the cluster structure as follows:

  1. You can add remove cluster nodes without modifying SCAN
  2. You can connect to a database without prior information on which cluster nodes the database is running

In the article an assumption is made that Oracle GI 11.2.0.X is installed and running using SCAN defined in /etc/hosts as shown below.

192.168.2.71 oel-cluster.gj.com oel-cluster

Oracle 11.2.0.3 is used for the testing the steps.
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November 10, 2011 Posted by | oracle | 2 Comments