Re: Raid and ORACLE

In our last gripping episode Liz Reen <lizr_at_geologist.com> wrote:
> In article <etkr1tkdrf843vuid4emti2v331cqd5kb2_at_4ax.com>,
> kremovethisspamthingthomas_at_gfsiinc.com says...
> > wtf? RAID 1, for redo is only expensive, but it effectively protect
> > your redo from disk failure (RAID 1 is mirroring) - writes are not
> > bad, and an reads can be satisfied from either mirror. Soooo, I
 don't
> > see the big issue with RAID 1, especially since disk is cheap. (you
> > should sitll of course do multiple sets - which ends up costing more
> > in disk).
> >
> > OTOH, you get better performance doing RAID 0 (striping) for redo,
> > and having multiple redo sets.
> >
> > But fired, eventually, why?
> >
> >
> > On Thu, 23 Nov 2000 11:55:02 -0600, "Jim DeCicco"
> > <decj1_at_interaccess.com> wrote:
> >
> > >I'd say that using Raid 1 would be closer to the optimal solution
 than it is
> > >to the worst solution.
> > >
> > >Jim
> > >
> > >>
> > >> Using RAID1 for redo log files should be just enough for you and
 your unix
> > >> admin to get fired, eventually.
> > >> --
> > >> Michael O'Neill
> > >> mjoneill_at_email.com
> > >>
> But Raid 0 offers absolutely no fault tolerance. The entire
 stripeset
> dies with the failure of a single disk. Not exactly where I would
 wish
> to put my redo logs or anything else I like. It is great for sort
 disks
> and tempfiles. Things that do not have to be backed up.
>
> My redos live on a striped mirror set. A striped mirror set is
 several
> mirrored disks which are then striped. You can lose one disk in each
 of
> the mirrorsets and still have a stripe set. Given that the costs of
> disks is so cheap there is no reason not to do this. ( When I first
> started in this business 1 gig was $50,000 plus controllers and
 cables)

>

RAID Level 6 provides extended data availability and protection when two disks fail at the same time or when a second disk fails during the reconstruction period resulting from the first disk failure. This may be a viable option for critical tablespaces. Of course you'll need to find a vendor whose storage arrays are certified for RAID 6 and since it is a bit more involved than RAID level 5 such arrays may be a bit scarce.

--
David Fitzjarrell
Oracle Certified DBA


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