Re: Combining snapclones with DataGuard

From: macdba321 <>
Date: Tue, 21 Oct 2008 05:42:30 -0700 (PDT)
Message-ID: <>

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. Received on Tue Oct 21 2008 - 07:42:30 CDT

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