Re: Still looking for RAID answers

<bdurrettccci_at_yahoo.com> wrote in message news:1104952703.087069.190780_at_c13g2000cwb.googlegroups.com...
> If you are doing a bunch of updating I would make one pair of drives
> seperate and put the redos on them. Make them really big since you
> have a whole drive for them.
>
> Then I would put the other drives that aren't hot spares into a raid 10
> array.
>
> For general random use it should be four times faster than having
> everything broken out randomly on pairs of mirrored drives.
>
> Now, if you have some special function where you put one huge table on
> a single pair of drives and do full table scans against it, that might
> make it worth breaking it out on its own drives. But, in general I
> would raid 10 everything but the redos.
>
> By the way, when I came to my current job their Sun boxes were just
> mirrored drives and they were honkin slow. Redoing them with striping
> sped them up a bunch. We also turned on direct io and dbwr io slaves.

Oh jeez, now I don't know what to do. Following the other replies to my request for help I had decided to set them all up as RAID 1 (individual mirrored drives). The databases supported by this system are all pretty much general use, no huge tables or other unusual considerations. I need to make the decision today, first thing tomorrow at the latest. Are you pretty sure that you got a performance gain simply swithching from mirrored to striped?

> Here are the parameters for those:
>
> dbwr_io_slaves=4
> filesystemio_options=setall
>
> - Bobby
>
> Randy Harris wrote:
> > I know that there has been much discussion of RAID recently in this
> > newsgroup. I hope to get a bit more advice from anyone who has
> experience
> > to offer.
> >
> > Several years ago, when I first become involved in Oracle
> administration, I
> > read much about the virtues of OFA. OFA proponents, and the Oracle
> DBA
> > Handbook strongly stated the importance of getting the various Oracle
> > objects onto different physical disk drives. More recently, at the
> > suggestion of several in this newsgroup, I've read about SAME (Stripe
> All,
> > Mirror Everything). It seems that the two are rather differing
> approaches,
> > though both generally urge the inclusion of as many physical disk
> drives as
> > possible. Both make it clear that RAID based on parity (RAID 3 - 5)
> are
> > undesirable. In simple terms, I suppose, we used to say that
> striping was
> > bad, now we say that only parity striping is bad.
> >
> > Because of a recent hardware failure, I am now in a position to
> completely
> > reconfigure my StorEdge array on a Sun server, running Solaris 8. I
> plan to
> > use 10 drives, keeping the other 2 for hot spares. If I consider OFA
> > recommendations, I would keep all of the drives as RAID 1 (mirrored)
> pairs,
> > with each pair, its own filesystem. SAME would have me use RAID 0+1,
> > creating a single slice of all 10 drives.
> >
> > It is still not clear to me, is the SAME architecture approach (RAID
> 0+1)
> > "better" than OFA (RAID 1), "just as good", or "almost as good" for
> Oracle
> > performance?
>
Received on Wed Jan 05 2005 - 14:06:44 CST