Re: Combining snapclones with DataGuard

From: Michael Austin <>
Date: Tue, 21 Oct 2008 22:14:05 -0500
Message-ID: <CSwLk.3028$>

macdba321 wrote:
> On Oct 21, 8:02 am, wrote:

>> On Oct 20, 10:05 pm, DA Morgan <> wrote:
>>> macdba321 wrote:
>>>> I read quotes from Ari Kaplan explaining how enterprises if possible
>>>> should (if possible and appropriate) combine the use of snapclones
>>>> (for SAN-to-SAN replication) with DataGuard.
>>>> I am confused how an organization could use both of these though. If I
>>>> am using snapclones, how can I also use DataGuard? What use would DG
>>>> provide? (Assuming that I am already snapclone'ing the database to the
>>>> secondary site.)
>>>> Can anyone shed some light for me?
>>>> Thanks.
>>> What also is missing, in addition to the items Sybrand listed, is the
>>> context.
>>> For a DR site I wouldn't touch snap clones as doing so one loses some
>>> of the most critical components of Data Guard Oracle brings to the
>>> table.
>>> Snapclones have their place but it isn't in DR. A DR site must be not
>>> just a 100% clean duplicate of production it must also be logically
>>> consistent. Something Snapcloning can not guarantee as snapping will
>>> efficiently replicate corrupt blocks.
>>> --
>>> Daniel A. Morgan
>>> Oracle Ace Director & Instructor
>>> University of Washington
>>> (replace x with u to respond)
>>> Puget Sound Oracle Users
>> Group,
>> As a long, long, long, time lurker, this is a horribly impolite
>> thread. I wish the posters here would ease up and try to share
>> knowledge instead of trying to be as mean as possible. Perhaps some of
>> us are new to the Oracle world, and others have been around for a few
>> years or decades, it should not matter. Try to help each other and
>> leave your egos at the door.
>> When I read the original posters question, I interpreted it as a
>> generic discussion. He/She (yes, there are actually females on here!)
>> did not provide versions or platforms. Nor did Ari Kaplan! It's a
>> generic discussion, how is DataGuard used in conjunction with
>> Snapcloning (in an effective manner)?
>> Yes, we all know that using old versions of the database, old
>> networking capabilities, old OS's, old keyboards, old mice, old .....
>> (you get the idea) will cause problems. Just assume we're talking
>> generic.
>> To the originial poster: at least you apologized and attempted to
>> explain yourself (albeit, somewhat sarcastically).
>> To those with the egos: Try to not be so rude, you may be new to the
>> Oracle or professional arena ... I have a feeling you'll go further if
>> you relax and try to help. But most importantly, feel free to not
>> respond if you have nothing constructive to add. Silence definitely
>> can be golden!
>> $Jen

> Well, as the original OP, I want to apologize to all. I did not intend
> to cause such a stir.
> Let me provide some lost information: The OS is Windows 2003 64-Bit.
> It is running (64-bit). There are no SANs (yet). The
> potential customer will buy 2 based on the pros/cons capabilities that
> my team outlines. They are a massive company and are planning on true
> enterprise class SANs (to be used to rearchitect the infrastructure.
> It is theoretical now, so saying the "latest & greatest" is not a
> stretch.
> My goal is simply high-high-level research for disaster recovery
> situational setups for the Oracle portion. There will be >1000miles
> between sites.
> I read Mr. Kaplan's presentation (and yes, I did e-mail him days
> ago ... but no response. I do not feel comfortable calling him via
> telephone). I saw his statement that storage methods of backup are
> "sometimes undiscovered in the world of DBAs". Mr. Kaplan goes on to
> say that array-based replication "Works best in conjunction with Data
> Guard by jointly reducing replication traffic and reducing or
> eliminating single points of failure" .... is he most likely referring
> to non-Oracle database files for the array-based replication, and DG
> for the database?
> Also, Daniel A. Morgan states: "A DR site must be not just a 100%
> clean duplicate of production it must also be logically consistent.
> Something Snapcloning can not guarantee as snapping will efficiently
> replicate corrupt blocks." I have read that DG can be used to detect &
> repair corrupt blocks (
> availability/pdf/corruption_wp.pdf). I have read that snap cloning
> software is able to detect a level of corruption (if it can not read
> the block, it can not propogate it to the destination filer.) Are
> these 2 levels of corruption? (Is DG able to detect a level of
> corruption that snap cloning software can not?
> Again, thank you for any information.

Just an observation - and not intending to start an OS war, but, if you are going to use enterprise class storage, why in the world would you ever deploy this on Windows? None of the Windows databases -including Oracle could ever hope to keep up with say, Solaris, AIX , HPUX or even Linux - and is far more manageable (IMO) than a Windows environment. Windows and even Oracle on Windows has it's place, I, however would not consider the data center one of them... Received on Tue Oct 21 2008 - 22:14:05 CDT

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