Poor performance with P35-DS3P

verukins wrote:
> Hi,
> I have recently purchased a P35-DS3P, installed 2003 64-bit and am
> experiencing absolutely terrible processor performance. Doing simple
> things run as running IE max's the CPU out according to perf mon.
>
> I have 8Gb ram and 4 x 500Gb WD SATA drives in a RAID 5 configuration.
>
> Pagining is not the issue (duh!) so im wonding if the supposed
> "hardware" raid actually offloads all its processing to the main
> processor ?
>
> can anyone comment on this ?
>

RAID5 requires an XOR (exclusive OR) logic operation. With four
disks, three of them get data, and the fourth receives the XOR
of the data on the other three. XOR is like parity, and if any
one disk goes missing, using the XOR operation allows reconstituting
the missing data.

http://www.z-a-recovery.com/art-raid5-variations.htm

With Southbridge based RAID5, XOR is done by the CPU. That means
all the data must be "munched" by the CPU.

On a real hardware RAID, there is an IOP (I/O processor). Usually
you see a thing with the heatsink and/or fan on top of it. That is
what does the XOR on a real RAID card. In addition, hardware RAID
cards can be equipped with a cache DIMM, which gives the potential
for the IOP to reorder operations. That is important for fractional
perations that normally require a read-modify-write. The fractional
operations can be deferred and head movement of the disks done in
the most efficient manner possible. (A card with a cache, may also
come with a battery, to hold the cache contents in the event of a
power failure.)

If you are having problems with compute performance, I'd try dropping
the amount of RAM, and test again. Just to see if there is a total RAM
component to your troubles. Note that the instruction flow through the
Core2 differs, depending on whether it is running 32 bit or 64 bit
instructions. You may want to check some benchmark results on the
enthusiast sites, as to how much difference that makes.

Paul
 >> Stay informed about: Poor performance with P35-DS3P 

verukins wrote:
> The effective of what you've said above is that the CPU does handle
> the raid operations....
>
> i think before anything else, i'll drop the raid and see what happens
> (which is not a good solution, but current performance is just
> horrendous)
>

Have a look at this article. It compares chipset RAID solutions, and
has some interesting numbers. And on this page, there is an option
mentioned, to enable write-back caching. And the mention of a UPS
is a good idea, no matter what flavor of RAID you end up using.

http://www.tomshardware.com/2007/01/03/the_southbridge_battle/page4.html

Paul
 >> Stay informed about: Poor performance with P35-DS3P 

Thanks for the comments paul - i do think that your making it more
complex than it needs to be though...

The RAID solution used on this M/B offloads all its processing to the
CPU.... so it is, by anyones standards, completely useless.

I've gone back to using software raid - and the performance impact is
tiny in comparison - and the box is now running acceptably.

I spose this should remain as a warning to other un-suspecting users
that the Intel raid solution on this motherboard is useless - and if
your buying a m/b looking for RAID, stay well clear of this piece of
junk.
 >> Stay informed about: Poor performance with P35-DS3P