Re: Remote Storage Mirroring vs Dataguard - Important

From: Ilmar Kerm <>
Date: Sat, 2 May 2015 09:05:10 +0200
Message-ID: <>


We are running storage replication offsite (in ASYNC mode) and we are currently working on replacing it with dataguard. Replicated databases are around 25TB.

  • We are also running ASM, every time we need to add/remove disk from ASM there is a huge amount of data that needs to be replicated (ASM rebalance). Initially added double/triple amount of free space didn't last very long, since the databases grew much faster that expected :)
  • We are running in ASYNC, if the replication lags the modifications are put into replication journal. If this journal gets 80% full or more, storage starts to throttle down IO on the source luns. From the database perspective it was a confusing problem to troubleshoot the first time. Also this problem is quick to arrive when doing ASM rebalance.


On Sat, May 2, 2015 at 5:19 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

Ilmar Kerm

Received on Sat May 02 2015 - 09:05:10 CEST

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