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RE: "wait for scn from all nodes" wait in RAC

From: Hameed, Amir <Amir.Hameed_at_xerox.com>
Date: Sat, 16 Jul 2005 13:05:35 -0400
Message-ID: <77A4D80DB2ADD74EB5D7F1D31626F0C00201627B@usa0300ms03.na.xerox.net>


Cary,
Based upon the explanation of this event, it seems like a legitimate concern. As for whether this event was a dominant contributor to the response time of an important business task, the answer is, I don't know at this point and I will have to isolate this by looking at waits at various time intervals and then see what ran during that time to narrow it down. But, it seems that this issue is not really dependent on a business event; it is the time it is taking for the roundtrip for the confirmation of the SCN so that the LGWR can write the redo. We are using three private gigabit interconnects and in theory there is enough bandwidth available to the IC path.  

Amir


        From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Cary Millsap

	Sent: Friday, July 15, 2005 4:47 PM
	To: oracle-l_at_freelists.org
	Subject: RE: "wait for scn from all nodes" wait in RAC
	
	

	Amir,

	 

	Only you can tell us whether the issue is of legitimate concern,
right? :-)          

        Is the event a dominant contributor to the response time of an important business task?          

	Cary Millsap
	Hotsos Enterprises, Ltd.
	http://www.hotsos.com
	Nullius in verba
	
	Visit www.hotsos.com for curriculum and schedule details...

	
________________________________


	From: oracle-l-bounce_at_freelists.org

[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Hameed, Amir
Sent: Friday, July 15, 2005 3:14 PM To: oracle-l_at_freelists.org Subject: "wait for scn from all nodes" wait in RAC Does anyone know what this wait (wait for scn from all nodes) is
about in RAC. We are currently running a test on a two-node RAC/11i instance. Statspack is showing this wait among the top five (at #5). We are using the "broadcast on commit" scheme as it is recommended by Oracle for 11i instances. Per Metalink, this event is related to the broadcast scheme that we are using. But what does it really mean and at what point it becomes a matter of concern? Any feedback will be appreciated.
	Thank you 
	Amir 


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Received on Sat Jul 16 2005 - 12:07:58 CDT

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