Re: Redo log & RAID

Yes, please use Oracle mirroring for redo. The Oracle LGWR executes extra instructions to ensure the integrity of each mirrored write in a way that hardware mirroring cannot do.

Unfortunately, if we had a dime for every bit of bad advice in an Oracle Press book, we'd probably have enough dimes to throw off the earth's rotation.

Cary Millsap

"Kirt Thomas" <kremovethisspamthingthomas_at_gfsiinc.com> wrote in message news:j8sbctg1jnq7db1ro2dn1ksccakgchub36_at_4ax.com...
> I'd say this is one of the areas the Handbook is dead wrong. The
> handbook pushes performance over reliability, and while performance is
> very important, it is not near as important ensuring the reliability
> of a production db :) Toss some more CPU's at the box and use
> Oracle's mirroring it's much safer.
>
> On Fri, 30 Mar 2001 18:45:09 -0700, Dale McD <dalem_at_rtd.com> wrote:
>
> >This excerpt from "Oracle 8i DBA Handbook" from Oracle Press, in the
 section on
> >Archived Redo Log File Mirroring:
> >"In general, you should favor the hardware system's mirroring solution
 over
> >Oracle's, provided the hardware system can suport mirroring without
 significant
> >performance impact. Mirroring solutions that use Oracle's methods or the
> >operating system methods are more portable across platforms buy may
 impact your
> >CPU usage."
> >
> >Once again, confused and uncertain. Ugh,
> >Dale M. (a newbie)
> >
> >> Question: is HW or SW mirroring a
> >> > better alternative to Oracle's mirroring of these files?
> >> >
> >>
> >> You need to have Oracle mirror them. Other types of mirroring most
 likely
> >> include one write request (HW mirroring definitly does) and if that
 write
> >> request fails, you are done for.
> >> Drop the Oracle mirroring and the day will strike you regret this
 decision.
> >>
> >> Regards,
> >>
> >> Sybrand Bakker, Oracle DBA
>
Received on Thu Apr 05 2001 - 23:36:26 CDT