Re: rac vs dataguard
- From: "ed lewis" <eglewis71@xxxxxxxxx>
- To: "David Ballester" <ballester.david@xxxxxxxxx>, <ksmadduri@xxxxxxxxx>
- Date: Fri, 17 Jul 2009 20:38:01 -0400
One thing I forgot to mention.
We will be setting up a physical standby
from the primary site, to a DR site.
----- Original Message -----
From: David Ballester
To: ksmadduri@xxxxxxxxx
Cc: eglewis71@xxxxxxxxx ; oracle-l@xxxxxxxxxxxxx
Sent: Thursday, July 16, 2009 2:19 PM
Subject: Re: rac vs dataguard
Hi:
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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