Re: DR and data replication on Oracle 9i Standard

On Dec 2, 1:43 pm, cqmman <cqm..._at_yahoo.co.uk> wrote:
> On 1 Dec, 15:36, DA Morgan <damor..._at_psoug.org> wrote:
>
> > It note that this is 9i but which editions? Standard or Enterprise?
>
> > Normally I would suggest EE and Data Guard if you are trying to create
> > a real DR (Disaster Recovery) site. Alternatively Streams would work
> > too.
>
> > I have seen DR sites built using snap-mirror / snap-restore
> > capabilities. And while they do work they are not as complete a solution
> > for an Oracle customer as is Data Guard.
>
> Standard edition.
>
> Yes, someone else has recommended DataGuard, but we don't have EE.
>
> I know there must a white paper on this somewhere, but can someone in
> a couple of sentences explain why DG is so much better than
> logshipping? Especially for someone with very little Oracle
> knowledge... Just not sure if it is worth upgrading our Oracle servers
> to Enterprise Edition..

http://www.oracle.com/technology/deploy/availability/htdocs/ha9i_listing.html The "cookbook" especially says it in a few pages better than I can in a few sentences. "When designing a solution that is critical to your business operations, you must ask yourself when, not if, a failure is going to strike."

It really isn't that difficult to use log shipping (after all, that was how it was done before DG), in 9i doing it yourself gives you control of things like being able to ship compressed logs, but it winds up requiring lots of manual labor to keep it going. You are reinventing the wheel, that will be reinvented better for you when you upgrade to 10. I do it, but then again, I'm paid by the hour, and even so, recommend not doing it this way if you have the choice. What really makes the difference is the quality of the network. If you have a crappy network (as my customer does), you are going to constantly be futzing with things to make it work, some of which would be automatic with DG. While DG requires some abstraction of the concepts and can be a steep learning curve for the novice, not using DG sometimes requires fairly advanced DBA abilities. For example, more than once the network or standby node was down for longer than the archives are kept online, requiring me to suck them out of RMAN backup pieces using PL/SQL with underdocumented commands like dbms_backup_restore.restoreBackupPiece (which one wouldn't have to use with O8 or O10). On the other hand, if you run into a DG bug where a network problem backfires into the production instance, you can have a very management visible problem. So be sure you have a recent version!

jg

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