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Re: Logical Standby Database 10gR2

From: DA Morgan <>
Date: Wed, 25 Apr 2007 21:10:05 -0700
Message-ID: <>

tinojam wrote:
> We are designing a DR plan for our production database which is a
> Oracle10gR2 RAC database with three nodes in the cluster. Based on our
> business requirements and cost constraints we have decided to build a
> logical standby RAC database (3 nodes) at our remote site. The
> business wants to use the standby database as a DR database and for
> reporting, 24X7. That is why I went the logical standby route. I have
> done the ground work in terms of checking that there are no
> unsupported data types for the logical standby db and everything
> checks out.
> Now the problem is this: the DBA team went to a presentation and an
> Oracle representative told them that they need a physical standby and
> a logical standby database to ensure the logical standby database
> works. He is saying that he wouldn't recommend having a logical
> standby db by itself, you need a physical standby database, based on
> best practices.
> Now the DBAs want the design to be changed to accommodate both a
> logical and physical standby database... extra cost and
> administration!
> Is there anyone out there just using a logical standby database for
> both reporting and DR without a physical standby?
> I have been working with standby databases since Oracle8i and I am
> sure the design is up to par. I want to get feedback from the group on
> this...

A logical standby is not a DR database. You can pretend it is but it will never give you business continuity and, if materialized views and indexes, etc. are created to support reporting ... when all is said and done it won't look like production either.

In short ... Oracle is right ... But what you likely can do is go from prod to your physical, using the physical to offload RMAN backups from prod. Then go from the physical to the logical and rather than making the logical a RAC cluster ... make it a standalone 2 or 4 CPU multicore box. That will help with financing doing it the right way.

Also, an important consideration, think through your implementation of Data Guard from cluster to cluster. The Oracle docs are incomplete and at any time any node or nodes may be off-line. The implications are important.

Daniel A. Morgan
University of Washington
(replace x with u to respond)
Puget Sound Oracle Users Group
Received on Wed Apr 25 2007 - 23:10:05 CDT

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