Re: Configuring Oracle on RAID 5

This whole RAID thing chaps my hide :) We were in the process of adding disk to our AIX (SSA and FCAL) system, and so, we decided to look at the new 'SAN' type products - IBM has it's Shark, and there are several others around. All of them however use RAID 5. We initially decided to take a pass, but a large company that's name starts with H, let us have there system on 90 take it or leave it basis. This system had a substantial write cache (6gb), but in overall performance, it was 'half as fast' as our existing FCAL disk subsystem (at RAID 0+1). (It equalled the SSA, but these were tired old 6000rmp SSA drives, that were faux striped). We ended up punting the E7xxx from H after they could find no way to get performance up to snuff. I found it humorous that the sales staff refered to RAID 0+1 as RAID 10 - (both IBM and H).

I saw an interesting implementation of RAID 4 (where the parity is written to only one drive) at OpenWorld. They made a pretty good case for this, mirroring the parity drive, and caching all writes. But you still have a write penalty eventually, and even with a large cache, it must be written to disk sometime :)

On Tue, 13 Mar 2001 23:07:19 +1100, "Howard J. Rogers" <howardjr_at_www.com> wrote:

>
>Nothing to do with the number of disks. If it were, RAID-0 would be
>interesting, would it not??!
>
>I'm not real hot on my RAID numbers, but IIRC (and I think I do) 0 is
>striping, 1 is mirroring (hence RAID 0+1 is striping AND mirroring), and
>RAID-5 is striping with parity. Real RAID gurus will tell you all about
>RAIDS 3, 4 and 6, but if you're like me, you will be asleep before they've
>finished.
>
>The numbers don'r relate to anything very much, just the standard to which
>that flavour of RAID adheres.
>
>Incidentally, RAID 5 works very well with 3 disks. Though, since I have
>shares in Seagate, I think it only fair to say that more is always merrier.
>
>Regards
  Received on Tue Mar 13 2001 - 07:39:19 CST