Re: Help! Oracle server clustering

Dusan Bolek wrote:
>
> That's not true. You can have cluster configuration which perfectly
> protects you from machine failure and also works as disaster recovery.
> It was discussed here recently.

I assume you're talking about a campus solution where one RAC node is in one building, another node in another building, and a synchronous hardware mirroring scheme is used to have a copy of the disk in each building? That's good, but it isn't pure disaster recovery for many businesses. That sort of solution is typically limited (if not by the disk vendors themselves then by basic practicality of performance) to a few kilometers. That won't do for many shops - just think of the WTC incident, or a big flood, earthquake, etc. True DR means hundreds of miles apart, and I've never heard of anyone running a real, business-critical, reasonably well-performing RAC system with that kind of geographic separation of nodes *and* disk. The speed of light is only so fast...

> Is interesting how Oracle people are insisting that RAC is for machine
> failure backup and you should use a stand-by (Data Guard) for disaster
> recovery (heard that couple of time this week).
> Which is simply not true.

It's mostly true. DG has many advantages over RAC in the configuration you're suggesting, cost, maintenance, and supportability being some of the most important. That makes DG the main DR choice for the vast majority of shops. Insinuating that Pete has some sort of ulterior motive for recommending what just about every shop out there uses for Oracle DR seems strange, esp. given Pete's track record of relatively unbiased advice on this forum.

> RAC can be a perfect part in your disaster
> recovery plans. The major difference between possibilities of RAC and
> Data Guard in terms of failure protecting, is delayed stand-by, which
> is a great feature if you don't believe your employees. Then Data
> Guard is the only option, but if you just want to be protected against
> fire, floods, Bin-Laden etc, then RAC is a sensible solution.

Again, I disagree. Delayed application of redo is a nice feature of DG, but it's hardly the main selling point. Price, performance, and simplicity are the main advantages, but there are many others.

Regards,
Sean Received on Fri Jun 28 2002 - 10:23:00 CDT