Poor performance with P35-DS3P

Discussion in 'Gigabyte' started by verukins, Jul 3, 2007.

  1. verukins

    verukins Guest

    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 ?
    verukins, Jul 3, 2007
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  2. verukins

    Paul Guest

    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.


    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, Jul 4, 2007
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  3. verukins

    verukins Guest

    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
    verukins, Jul 4, 2007
  4. verukins

    Paul Guest

    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.


    Paul, Jul 4, 2007
  5. verukins

    verukins Guest

    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
    verukins, Jul 5, 2007
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