Re: Max IO size

Check that your multiblock_read_count setting didn't get truncated to an OS limit. If you set it to 64, which would mean "64 8k blocks to be read in a multiblock read", you'd look for a 512k read. However, if the OS limit is 256k reads, then Oracle would truncate multiblock_read_count to 32 ( based on your 8k block size ).

Take a look at the setting in the SGA to make sure it matches your init.ora setting, as Oracle will quietly set it to the platform specific max value.

-Kevin
"Connor McDonald" <connor_mcdonald_at_yahoo.com> wrote in message news:3B966E0C.3BA_at_yahoo.com...
> I've got a sun (solaris 2.8) box with with datafiles under vxfs. After
> setting
>
> - maxphys to 512k
> - vxiomax to 512k
> - db block size to 8k
> - multiblock read count to 64
>
> I had presumed that I could get a ceiling of half a meg per read on
> (say) a full table scan, but a level 8 10046 trace yields a ceiling of
> 256k (ie p3 in the waits is 32 not 64)
>
> I'll be repeating the test under a raw partition tomorrow but comments
> anyone ? As a related question, anyone know what Oracle's SSTIOMAX is
> under the various versions (say from 7.3)
>
> Cheers
>
> --
> ==============================
> Connor McDonald
>
> http://www.oracledba.co.uk
>
> "Some days you're the pigeon, some days you're the statue..."
Received on Wed Sep 05 2001 - 15:56:04 CDT