Currently our production is running on 10.2.0.1 RAC. I need to upgrade to it to 10.2.0.5 RAC. Do I test my application on 10.2.0.5 RAC ??? Or testing application on 10.2.0.5 stand-alone is enough??
Need your valuable suggestion
Ideally, you should test with exactly the same configuration you are going to use in production – in your case 10.2.0.5 RAC.
On a separate note – why not upgrade to a higher version. Newer Oracle versions are so much better and would be supported for a long time...
Your testing environment should match the exact version, including PSUs and interim patches, as your production environment. If you have a test RAC cluster (which shouldn't be a problem considering you could always virtualize a test environment), that would be ideal. That way you could test both the PSU installation and application against the testing environment before touching anything in production.