Re: rac vs dataguard

I'm agree with the points about application scalability, performance, etc... but what's about D&R? For performance you can always tune your application / Oracle / OS layer or add more nodes to the RAC but If you loose the primary site or the whole RAC ( big disaster or big human error ) you will must:

• locate new hardware ( new host ) or make room on existing one.
• Install software ( OS, Oracle binaries, patchsets... )
• restore the whole database and recover as far as you can ( lost some of the newest redo logs ? )
• Start to give service.
• If some data was lost, tell your people to redo it again ( if it's possible )

With the Data Guard you have it done in a few minutes, and near zero data lost.

If you can survive without giving service for all the hours ( days? ) doing the previous steps, go on adding only new nodes to the RAC

But if service is important to you, you can spend a little more money on the iron ( is not so expensive this days ) and mount a Data Guard

You can mount a physical standby to protect the whole service and in the same host, mount a logical standby for reporting purpouses, using both of them the same binaries.

Define the resources for the physical standby as low as possible ( it only will be doing recovery ) and allow more resources for the logical one

If a big disaster occurs, you can activate the physical standby ( modifiying init to allow more resources ) and point the logical one to adquire data from the new primary, as part of your contingence procedure.

What's your opinion?

Regards

D

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