Re: Recommended stripe depth for Oracle on a Raid?

your DB_FILE_MULTIBLOCK_READ_COUN*DB_BLOCK_SIZE should be equal to OS maximum I/O

stripe size should be DB_FILE_MULTIBLOCK_READ_COUN*DB_BLOCK_SIZE divided by stripe width

so if you have 256k, 8 disks in RAID-0 your stripe size should be 32K

this is my theory and used in practice and the performance isnt too bad, acceptable

Not a storage expert, just use some common sense and read experts recommendations....

Rick Denoire <100.17706_at_germanynet.de> wrote in message news:<u6g0qvshjr9aicceo37hg3bfdfje06571a_at_4ax.com>...
> In the next weeks, I will have the seldom opportunity to rebuild the
> storage containing the DB. All file systems will be reformated.
>
> We are using a CX-400 (Dell/EMC) connected via FibreChannel to a Sun
> Server; Oracle is 8.1.7 by now but will be 9.2.0.4 after rebuilding
> the Raid.
>
> Papers I have read say that for Oracle, one should set the stripe
> depth (the amount of data in KBytes per Disk) according to the product
> (Oracle block size X DB_FILE_MULTIBLOCK_READ_COUNT), in my case:
> 8x32=256K.
>
> I just don't understand this theory. That would mean that every I/O in
> a full table scan would only read from one disk at a time, one disk
> after the next - bad.
>
> However, somewhere else a rule of thomb is mentioned saying that the
> total amount of data per I/O (i.e. blocksize x
> DB_FILE_MULTIBLOCK_READ_COUNT) should correspond to the stripe width.
> The stripe width is (the stripe depth X the number of disks in the
> raid group) - we have 8 disks (+1 parity +1 spare). This advice seems
> more reasonable to me, because every I/O would be serviced by ALL
> disks in parallel.
>
> So what do you recommend? The number of users is about 5, but they use
> batch jobs spending hours with DB work.
>
> Thanks a lot
> Rick Denoire
Received on Thu Oct 30 2003 - 02:19:58 CST