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I have some problems with disk performance. I have 6 x WD 500Gb RE4 disks. Each disk gives 135Mb/sec throughput. All measurements are made with hdparm with options "-tT" (I know that it is just synthetic test, but I need some start point to make measurements).

I have controller with Sil3124 x 4 ports PCI Express 1x

So...

  1. RAID0 on controller with 2 disks gives 200Mb/s - ok, pcie limit.
  2. RAID0 on motherboard with 2 disks gives 270Mb/s - niceeee :)
  3. RAID0 on contorller with 4 disks gives 200Mb/s - ok, pcie limit.
  4. RAID0 on controller with 4 disks + 1 disks on motherboard = 340Mb/s ... :(
  5. RAID0 on controller with 4 disks + 2 disks on motherboard = 300Mb/s .... why? Any ideas? Maybe need more cpu power?

Now there is Pentium D Dual core 2.8Ghz, 4Gb RAM. It is dedicated box for storage.. no other activity.

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> It is dedicated box for storage.. no other activity You use Raid0 for a storage box? Seriousely? Why? Try to run "top" during the read/write tests, maybe we can troubleshoot your problems with a little more informations. –  Andrea Giardini Sep 6 '12 at 8:14
1  
If you're looking for a fast way to lose all your data then a simple "sudo rm -rf /" might be marginally faster than what you're trying. –  Chopper3 Sep 6 '12 at 8:42
    
Does the server hold any critical data ? –  Luis Ventura Sep 6 '12 at 9:04
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@user134880, just in case you've missed the subtle hints by everyone else - DON'T USE RAID 0 - ever. Why any controller even allows it (on its own) is a mystery. –  John Gardeniers Sep 6 '12 at 9:38
    
any comments to question? :) –  user134880 Sep 7 '12 at 9:30
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1 Answer

Depending on what controller you use it may be utilizing your built in CPU, so the more disks you add the more CPU will be used when doing huge transfers. So your CPU might indeed be your bottleneck.

Apart from that:

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I'm using raid0 to get maximum possible performance. It's just for test. Later there will be raid10. The question is not raid0 or not. Thank you for advise, but now I just try to get maximum throughput "just for fun". By saying that it is dedicated storage box, I want to point that there is no other cpu activity, to avoid answers like "software raid share cpu with other processes" ... –  user134880 Sep 6 '12 at 16:16
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