Re: Still looking for RAID answers

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.

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 - 13:18:23 CST