Re: Remote Storage Mirroring vs Dataguard - Important

From: Mladen Gogala <>
Date: Wed, 06 May 2015 10:50:30 -0400
Message-ID: <>

On the other hand, you can do storage replication, without consuming an Oracle license. Essentially, you can just replicate your storage and, if switchover is needed, restore the Oracle software from backup, bring up the instance and go on. Saving on Oracle licenses is a BIG plus.

On 05/05/2015 02:22 AM, Svetoslav Gyurov wrote:
> Hi Sanjay,
> I used storage replication many times to copy prod to dev or take a
> snapshot before some major activity but never used it in a way as a DR.
> To answer your questions:
> - I would prefer DG because it's much more flexiable. You've got an
> idea what is the transport lag, apply lag and what is the state of
> your standby. You can open the standby as readonly, ADG or ever
> snapshoot standby to do some testing. Switchover is just a matter of
> one command through the broker. I cannot see neither of these
> happening with the storage replication.
> - It should be fine, as long as you replicate all the ASM LUNs. If you
> open the standby database you'll always have to do instance recovery,
> keep that in mind.
> - Yes, you can have your storage replication in SYNC. Pretty much it's
> similar to DG - the blocks from the first storage arre written to the
> cache of the second storage and they an acknoledgement is sent.
> - Not sure what the question is but if you have a GAP the storage
> systems are smart enough - and because we are only replicating blocks
> they can assisiliy recover the gap and become in sync again.
> - The fastest and safe way to bring the standby database in consistent
> state is by using DataGuard broker.
> - Modern storages have the option to change the direction of the
> replication so this shouldn't be a problem.
> Regards,
> Sve
> On Sat, May 2, 2015 at 4:19 AM, Sanjay Mishra
> < <>> wrote:
> Can anyone share their views on the following on Real practical
> experience with the setup in their environment. I had worked with
> dataguard but never with Storage Replication for Disaster recover.
> Some points for the required environment which can affect or help
> in providing or sharing the experience
> * Oracle 11g 2-Node RAC setup using ASM on both Primary and DR site
> * Database size range from 1-5Tb
> * Database has lots of DML activites on daily basis
> Questions:
> * What is the best option to be used for Disaster Recovery when
> has to choose Storage Replication vs DataGuard for RAC setup
> and if can provide why you think one preferred over other as
> per your experience ?
> * Does there can be issue if Primary storage or server crashed
> and Recovery either failed to start the Datbase on DR or lost
> some data ? Keeping in mind that we are working in SYnc Mode.
> * Is Storage mirroring can be setup so that both Primary and
> Remote storage is almost SYNC like Synchronous Data Giuard
> Setting ?
> * Is it possible that we may loose the DR location and Storage
> Replicated environment failed to start ?
> * Which one is faster to bring Database live, Storage mirrored
> DR env or Dataguard based environment?
> * How to go back or switch back to original Primary when you
> have done switchover initially to DR location ? In Oracle
> Dataguard we can go back using Flashback DB feature and
> reinstantiate the database
> * Any other Pros and Cons for both option as well as any good
> Link to be checked.
> Sanjay

Mladen Gogala
Oracle DBA

Received on Wed May 06 2015 - 16:50:30 CEST

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