Difference Between RAID AutoDetect and RAID On

Discussion in 'Dell' started by Monica, Mar 12, 2009.

  1. Monica

    Monica Guest

    Maybe you can explain it to me like I'm six :)
    I'll have 4 SATA hard drives on my XPS 420 with XP SP2
    Two internal SATA drives and two external.
    I won't be "mirroring" my C drive and I want all
    the hard drives to operate as they were intended.
    So, is "RAID On" necessary? Does this mode
    cause the drives to react slower?
    Monica, Mar 12, 2009
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  2. Hi!
    It depends upon what choices you are offered in setup. There are two
    or three depending (excluding "disabled or "off") upon your system:

    Compatible emulates a PATA controller and drives. This is compatible
    with operating systems that don't know and understand the improvements
    SATA controllers and drives had to offer. This requires no special
    driver support, but it is the least performing option.

    AHCI mode allows the full capability and speed of the SATA controller
    to be recognized. You may require a driver when installing Windows to
    make use of this mode. Dell typically includes the driver you need
    with their Windows XP install discs. RAID is turned off in this mode.

    RAID ON mode is sometimes shown as combined with AHCI mode in Dell
    system setup. In this mode, a special driver is required for Windows
    to be able to see your hard drives. This is on a Dell Windows XP
    installation disc. If you want a RAID array, you set it up later with
    the Intel Matrix Storage Manager tools. As best I remember it, the
    drives will function independently of one another in this mode unless
    you explicitly configure them to do something else.

    AUTOMATIC...well, I haven't seen that one on any of my Dell systems
    (Dim8400, OptiPlex 210L, OptiPlex GX620 desktop) that have RAID/AHCI
    capability in their SATA implementations. My guess is that it would
    take a look at the drive configuration and your OS to determine the
    correct operating mode.

    The RAID ON mode should not cause a reduction in performance even if
    you don't end up using RAID. In reality, the difference between each
    operating mode will be minimal. You usually end up waiting on the
    drive mechanism to come up with the data, even with older systems that
    use PATA drives.

    William R. Walsh, Mar 12, 2009
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  3. It should also be noted that if you change this setting after
    installing Windows, you may make your system (temporarily) unbootable.

    William R. Walsh, Mar 12, 2009
  4. Monica

    Fixer Guest

    Fixer, Mar 12, 2009
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