I have found this as well -
I have a nice simple example of a program that loops and occasionally
writes a block to a file.
On a 2 cpu machine, running 2 of these processes in parallel takes twice
as long as running just 1 process!
However if I comment out the IO, then 2 processes takes the same elapsed
time as 1.
My conclusion is there exists some sort of "big" lock on access to the
ATA array.
I believe that 3ware have a non blocking implementation of ATA RAID -
I intend to sell the Promise and obtain a 3ware in the next month of so
and test this out.
regards
Mark
Andrew Sullivan wrote:
>That said, even the 2-way RAID became almost uselessly slow when
>multiple queries were running -- indeed, dramatically slower than a
>plain single IDE drive.
>
>
