Re: RAC clarifications

  • From: Guillermo Alan Bort <cicciuxdba@xxxxxxxxx>
  • To: debra.scarpelli@xxxxxxx
  • Date: Thu, 17 Dec 2009 19:18:03 -0200

Someone once pointed in this list, that having no scheduled downtime is
unrealistic... and it would end up with unscheduled downtime. So I suggest
you reviste that part of the question ^_^

As for patches that allow rolling upgrades... well. there aren't that many,
and mostly no CPU allows it (requires startup upgrade, so...)

I'm given to understand that there are some patches that can be applied
online in 11g... but think of it this way: Applying a patch online means
changin a binary or something in the dictionary... that could lead to a
whole lot of trouble and require consistent copies of libraries and
binaries... this is something very hard to accomplish, if at all possible.

On the other hand, there is no 0 downtime solution with Oracle. There is a
'very little downtime' solution, which is RAC + DG... which has a lot of
issues still. But still, in the event of the ENTIRE RAC going down, there
would be a downtime, minimal, but downtime at last.

As mission-critical systems go, not counting custom systems, Oracle RAC + DG
is the best money can buy... the question would be... how much are you
willing to spend...

A six node RAC with a TAF enabled application would have virtually no
unscheduled downtime, and minimal scheduled downtime (make sure you use
separate homes) even a three or four node version of that would work...


On Thu, Dec 17, 2009 at 6:40 PM, <debra.scarpelli@xxxxxxx> wrote:

>  Hello all, and thanks in advance for your input on these questions.
> For those of you who are familiar with RAC, in your experiences, how often
> are the patches (include vulnerability patches) rolling patches (i.e. no
> downtime) vs. non-rolling patches (downtime required)?
> And if anyone is using the combination of RAC with DataGuard – do you find
> this truly provides a no-downtime solution in the event of hardware failure?
> What are the drawbacks/gottchas if any?
> We’re comparing a number of RDBMS solutions for a 24x365 requirement,
> including RAC. I’ve been an Oracle DBA for sometime, but not yet used RAC,
> so your experience is most appreciated!

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