RE: RAC global cache

From: Oliver Jost <>
Date: Tue, 10 Jun 2008 13:47:40 -0400
Message-ID: <DB508580748FAD4692628A58C4E653F504074F4F@MAIL01.Corp.FC.LOCAL>

Thanks All,

   The question has been answered. As to running in single instance, there is a way to place the database in single instance mode (though not recommended) by using you can decouple the rac binaries.... but, getting it back may not be so simple.  


From: Frits Hoogland [] Sent: Tuesday, June 10, 2008 12:44 AM
To: Oliver Jost
Subject: Re: RAC global cache

All the normal RAC rules apply to a database where cluster_database is set to true. I am not aware of any single instance RAC optimisations
(nor can I think of any reason), which means the normal steps are
followed. Probably the callout on the interconnect is not made, because the RAC cluster knows there is only one instance (every instance has to join the cluster explicitly). I haven't tested this explicitly, though.

This should mean some gc waits can be seen, but because there is only one instance, waits like global cache cr request should be minimal.

Because the 'resource mastering' shifts from two nodes to one node upon bringing down one node/instance, this can result in some waits during the remastering. (this phenomenon can be detected in the alert log, if I'm not mistaken)


On Thu, Jun 5, 2008 at 10:38 PM, Oliver Jost <> wrote:

	Hi All,
	   When I bring down one instance in a 2- node RAC environment

(CRS still up, AMS still up, Solaris 9, Oracle I still see
wait events relative to global cache activity? I'm wondering if anyone might clear this up for me. When a block isn't found in the local cache is LMS still busy checking across the interconnect? Do we still get global cache cr request and global cache cur request waits while the living instance determines whether the request will be fulfilled?          
	Thank you, 

Received on Tue Jun 10 2008 - 12:47:40 CDT

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