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

From: Kevin Closson <kevinc_at_polyserve.com>
Date: Sat, 16 Jul 2005 15:04:13 -0700
Message-ID: <B9782AD410794F4687F2B5B4A6FF3501021D4628@ex1.ms.polyserve.com>

> 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
> enough bandwidth available to the IC path.

bandwidth of the interconnect is most likely not a problem. Latency? Perhaps.
Processor spikes/saturation on certain nodes, more likely.

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 - 17:06:13 CDT