RE: What does an app need to do to work with RAC

Please make sure that you correctly "identify" and apply all the 11i patches that are needed for the 11i apps to work with RAC. I know it too well because we were bitten by a patch that we were told not to apply (by Oracle). Also, when you test your apps, make sure that you test every functionality that currently exists in production. For example, we never test printing in our production-simulated test environment because the business had decided a long time ago not to print when running tests that simulate production volume because we print a lot in production. Guess what; the 11i patch that we were told not to apply ONLY shows its impact when you print and that is why we did not catch it in testing and until the implementation day and by that time it was too late to do anything because the impact was so severe that the apps was crawling and we had to rollback the entire implementation. The message that I am trying to convey here is that when it comes to configuring 11i with RAC, the task becomes a little more complicated. If you need information on the 11i patch then I can forward it to you.  

Amir

        From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Anand Rao

	Sent: Monday, January 29, 2007 9:42 AM
	To: john.hallas_at_hcresources.co.uk
	Cc: oracle-l_at_freelists.org
	Subject: Re: What does an app need to do to work with RAC
	
	
	John,
	
	allow me to recommend,
	
	Chapter 16 - Developing Applications for RAC
	Oracle Real Application Clusters Handbook - K Gopalakrishnan
	

http://www.amazon.com/Database-Application-Clusters-Handbook-Osborne/dp/ 007146509X/sr=1-1/qid=1169465566/ref=pd_bbs_sr_1/105-4962592-3676461?ie= UTF8&s=books
<http://www.amazon.com/Database-Application-Clusters-Handbook-Osborne/dp /007146509X/sr=1-1/qid=1169465566/ref=pd_bbs_sr_1/105-4962592-3676461?ie =UTF8&s=books>         

        KG and i have documented some, if not all the reasons for an application not to work or scale on RAC. Note that the brief chapter is a discussion from a scalability / performance perspective and not necessarily from an operational / functional view, as your question seems to hint.         

        there is a need to define what you mean by "might not work on RAC"         

1. application won't start? are you are referring to a complete breakdown of the application / database?
2. application "hangs" or doesn't respond after startup and connecting to database?
3. transactions don't complete "on time"?

        and so on...         

        if you are able to describe your apprehensions clearly, then you might get some more clues and answers.         

        As Anjo very rightly and accurately mentioned, contention is your biggest problem. The way in which your application accesses the data is a key factor and this is also what Tim has said very correctly in the orafaq forum.         

        Mladen does have a point. unless you know what each software module does inside the Oracle kernel, you may not find much use with x$kcbsw. Oracle Support might help you with that, if not the evangelists in this forum.         

        hope that helps,         

	best regards
	anand
	
	
	On 29/01/07, Boris Dali <boris_dali_at_yahoo.ca> wrote: 

		John,
		
		For what it's worth I asked a somewhat related
		question back in 2002 and found Tim and Cary's replies 
		very informative. I think they are still relevant.
		Here's the link:
		
	

http://www.orafaq.com/maillist/oracle-l/2002/11/29/2163.htm                 

		Thanks,
		Boris Dali.
		
		--- John Hallas <john.hallas_at_hcresources.co.uk> wrote:
		


		> I will show my ignorance here and ask for what

		> reasons an application 

		> might not work with RAC when more than one instance

		> is added.

		
		
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