Re: Remote Storage Mirroring vs Dataguard - Important

That is definitely a (major) "fly in the ointment" for storage-level replication. Its defintiely worth keeping in mind for the day I have to make this decision myself.

Thanks for the tip.

On Sat, May 2, 2015 at 3:05 AM, Ilmar Kerm <ilmar.kerm_at_gmail.com> wrote:

> Hi
>
> 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.
>
>
> Ilmar
>
>
> On Sat, May 2, 2015 at 5:19 AM, Sanjay Mishra <dmarc-noreply_at_freelists.org
> > 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.
>>
>> TIA
>> Sanjay
>>
>
>
>
> --
> Ilmar Kerm
>

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