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Thread: Troubleshooting a REALLY Slow RAID 5

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    Join Date
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    Ubuntu 9.10 Karmic Koala

    Troubleshooting a REALLY Slow RAID 5

    Can anyone help me troubleshoot my RAID 5 Array? I'm getting write speeds of 5 MB/sec and UNDER. The platform isn't that old, so it doesn't seem like it should be going that slow. I've tried what I know to check, but I've got lots of data on the array right now, so I haven't used some of the benchmarks that wipe data. Everything looks good. So I'm really at a loss.

    Some details:

    The server runs 10.04 with an AMD Athlon 3000 and 4 GB RAM. I added a PCI expansion card to get 4 extra SATA ports for all the hard drives. I think all the RAID drives are connected to that card, and I'm sure that can, technically, limit speed by quite a bit, but I still can't see it bringing writes down to less than 5 MB/s. Sometimes less than 1MB/S.

    There are two 500 GB drives arranged as "Just a Bunch of Disks" for a total of about 1TB.

    Then I have that and two other 1TB drives set up as the RAID 5. The partition is ext3 and shared via NFS to another desktop. If I navigate there via Nautilus on the other desktop and start copying files, that's where I get the low write speed.

    Where should I start looking for problems?

    Edit: I should have also noted that the OS is on a separate 20GB IDE drive. Reads and writes on that are appropriate for the drive I'm using. And if I SSH into the server and start creating either large or small files on the array, I see the same speed problems. So it's not a data transfer problem with the network. It's a Gigabit network and I can watch full 1080p content from the server via NFS without any problems.
    Last edited by Joshua; December 11th, 2010 at 05:44 PM. Reason: Left off some info

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