Re: Just passed 8i OCP

Well, I'm not Daniel but I'll jump in anyway!

"FC" <flavio_at_tin.it> wrote in message
news:lHQ29.162192$Jj7.3612288_at_news1.tin.it...
> >
> > 1. When should you consider creating more than two control files?
> > 2. Are there conditions under which you should not create a large number
> > of control files?
> > 3. If you create multiple control files how should they be distributed
to
> > optimize scalability and performance?
> >
> > Now that kind of knowledge has value.
> >
> > Daniel Morgan
> >
>
>
> By the way Daniel,
> when should I consider creating more than one control file ?

When you choose to install Oracle. In other words, absolutely no Oracle database should ever have just one Control File. Multiplexing the Control File protects you against corruption or loss of the control file (hardware mirroring only protects you against physical loss). With only one Control File, loss requires a hideously expensive resetlogs operation, or the use of a create controlfile script. With 2 or more, recovery simply involves copying a surviving copy into the destination formerly occupied by the missing one.

> I thought it was depending more or less on the number of disks.

Yes and no. Obviously, to protect against hardware failure, it would make most sense to house each controlfile copy on separate disks. But you get protection against corruption wherever you put the copies.

> The installation wizard defaults to three, perhaps they think you should
not
> even try to use Oracle unless you have a minimum of three physical drives,
> which means buying 9 disks if you want a Raid-5 system, but now I
understand
> there is more to know about this subject, so please share the recipe!
>

It defaults to 3 because 3 is about the right number! You've got protection, and redundancy of protection. More than three is really just paranoia (and potentially causes performance worries, as each copy needs to be maintained correctly at every checkpoint). There's a maximum of 8, in any case.

Regards
HJR
> Thanks,
> Flavio
>
>
>
Received on Sat Aug 03 2002 - 14:54:06 CDT