RE: RAC and Data Guard Configuration Question

From: Goulet, Dick <>
Date: Wed, 7 May 2008 11:23:45 -0400
Message-ID: <>

Step number one, what is the purpose of your DR site? Is it supposed to handle 100% of normal expected load or something less? The answer, which has to come from management, with end user buy in, will tell you if 3 nodes are sufficient or you really need 6.

Dick Goulet / Capgemini
North America P&C / East Business Unit
Senior Oracle DBA / Hosting
Office: 508.573.1978 / Mobile: 508.742.5795 / Fax: 508.229.2019 / Email: 45 Bartlett St. / Marlborough, MA 01752

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-----Original Message-----
[] On Behalf Of Martin Klier Sent: Wednesday, May 07, 2008 9:32 AM
Cc:; Subject: Re: RAC and Data Guard Configuration Question


maybe it's an option to use huge nodes with a better peak performance. This will be useful for the single-instance-recovery as well.

But it's not cheaper, by far not.


Dan Norris schrieb:
> Chris,
> As Martin pointed out, for the "normal" case where DR is just
> recovery, only one instance will be used to apply all redo. However,
> case you should be more concerned about is what happens when you
> actually activate the DR site and try to run production there. If your
> production workload requires 4 or 5 nodes in your current 6-node
> production site, then trying to place that workload on 3 nodes will
> result in a complete outage and negate any DR benefits you were trying
> to achieve. In fact, it's almost worse since you'll be trying to run
> the DR site, failing, and likely will be troubleshooting the resulting
> issues on the DR site. Meanwhile, no one is working on trying to get
> primary production site back up and running.
> In no case would I consider running two instances on the DR servers
> since that will probably just make things worse by carving up each
> server's resources (CPU, RAM, I/O) for two instances. I don't think
> worry about instance naming since all applications should connect via
> services (where service_name <> instance_name) anyway. I would use the
> same service names on the DR site as I have on production, though.
> Shouldn't be a requirement, just might make things easier.
> GL!
> Dan
> Chris Dunscombe wrote:

>> <snip>
>> On the DR site we only have 3 nodes, we'd like 6 but 3 is all that
>> we're going
>> to get.
>> The question is should we configure DR to have 1 instance per node
>> (same as
>> production) but this leaves only a total of 3 instances and hence 3
>> redundant
>> UNDO tablespaces etc or have 2 instances per node?
>> Also is it best practice to have the instance names on DR the same as
>> production.
>> Any experiences, advice, "best practice" etc. for this is most

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Received on Wed May 07 2008 - 10:23:45 CDT

Original text of this message