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Thread: RAID5, 6 disks, dualcore 2.4ghz

  1. #1
    Join Date
    Oct 2007
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    Question RAID5, 6 disks, dualcore 2.4ghz

    I'm looking to software raid5 using the following:

    ubuntu server 8.04
    athlon 64 3800+x2
    DFI SLI-DR motherboard
    1x 250gb for /
    6x 250gb for /media/data (IDE for the moment, will swap these for 1tb sataii drives eventually)

    What kind of write speeds can I expect using this setup (system will be almost completely dormant for cpu/ram use). Really, I just want it to be over the standard 100mbit throughput for write, read of course will be massive. This is for home experimentation, as well as real-world use for my home network.

    I will be using this page as a guide to getting it setup, but the part with gparted is a problem -- this box is headless and has no gui installed. Is there a method to flag a partition as a raid-partition? Also, how does mdadm tell me I have a failed drive?

    Edit- Do I need to enable CONFIG_MD_RAID5_RESHAPE=y in the kernel before I can grow the raid? Or is that enabled in the latest kernel builds?
    Last edited by Der_Idiot; May 25th, 2008 at 09:10 PM.

  2. #2
    Join Date
    Oct 2007
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    26

    Re: RAID5, 6 disks, dualcore 2.4ghz

    Looks like after looking at my kernel configuration, the raid5 growth command is already set to yes.

  3. #3
    Join Date
    Oct 2007
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    Re: RAID5, 6 disks, dualcore 2.4ghz

    ... no response? Come on guys!

  4. #4
    Join Date
    Feb 2007
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    Cameron Park CA USA
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    Distro
    Ubuntu Development Release

    Re: RAID5, 6 disks, dualcore 2.4ghz

    I think your DFI motherboard uses PCI-E to drive the SATA controller for your drives. The sequential read speed of a 6-drive raid5 array will be about five times what one drive would be. If your drives are late model ones with a thourhgput of about 50MB/sec then you will see 250MB/sec, that's bytes/second. If first generation perpendicular ones then it'll be 350MB/sec. The write speed will be just a little less.

    The motherboard PCI-E is likely X1 and that taps out at 500MB/sec. If you are using 2nd generation perpandicular drives then you will over run the bus, as each of these drives is good for 100MB/sec throughput.

    Uses parted to create your partitions in your server, headless. If you use mdadm you might not even need to have the drives set for "raid". I didn't once or twice and all worked out just fine.

    Good luck!
    Last edited by fjgaude; May 28th, 2008 at 07:52 PM.
    Regards, frank, at http://yantrayoga.typepad.com/noname/
    Homebuilt Lian-Li PC-Q30X Intel i5-4670K 4.0GHz, SSDs, 16G RAM | Dell laptop E1505n, netbook 10n
    Oracle VBox w/ WinXP Pro running Xara Designer, PaintShopPro, and InDesign CS.

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