Re: Warehouse Stripe Size with Oracle8

Well, I've only tested on AIX, but the best performance overall came with 64K - which just happens to be the figure Oracle/IBM recommend. We run around 1TB of Oracle datawarehouses on raw disk, and always now use the 64K stripe size. Check with the Oracle docs for your platform for an appropriate figure and back it up with some testing.

Steve Phelan

(Oracle 7 & 8 OCP)

howard.galusha_at_thehartford.com wrote:

> I am a data warehousing consultant working with Oracle8. I have some
> experience with Oracle on UNIX, but I'm certainly not a DBA and I'm looking
> for advice with the following issue:
>
> We are running Oracle 8.03 on a 4-way DEC Alpha under VMS (please don't ask
> why, it is a long story.) We have over 300 GB of disks, set up in various
> RAID arrays (RAID 1, RAID 0+1, RAID5).
>
> Our system DBA's set up the Oracle blocksize to be 32K (to oltp folks, that
> may sound somewhat high, but for data warehousing, it's considered kosher.)
> The disk arrays were set up with a 512 byte stripe size.
>
> Now, intuitively, the stripe size sounds way too small - I picture the o/s
> getting swamped performing 64 i/o's to read 1 Oracle block (and in data
> warehousing, you are reading lots of blocks). Now apparently the disk
> controllers have a 32 MB cache to mitigate that somewhat, but I've read
> information (page 58 of Oracle8 Data Warehousing by Dodge and Gorman, Oracle
> Consulting's Physical Database Design Guide by Rainer Runge) that says the
> minimum stripe size should be at least 2X the DB_BLOCK_SIZE.
>
> This has been deemed "probably correct in theory" by our VMS team, who are
> unwilling to change the set up based on anything other than practical
> experience (they haven't had any problems with 512 bytes in their oltp
> systems and this is their first encounter with a warehouse.)
>
> Does anybody out there have any "practical experience" with striping an Oracle
> data warehouse under VMS, or have enough Oracle/VMS experience to refute the
> recommendations from Oracle and Mssrs. Dodge and Gorman? I'm concerned that
> proceeding with this set up will burn us and will be a ton of work to "undo".
>
> Thanks,
>
> Howard Galusha
>
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Received on Fri Feb 19 1999 - 15:17:24 CST