I'm getting slower than what I would have expected on an external raid box (https://www.scan.co.uk/products/4-bay-icy-box-ib-rd3640su3-external-raid-system-for-35-sata-hdd-with-usb-30-plus-esata-host)

I have connected via Sata on a sata card (https://www.scan.co.uk/products/lycom-pe-130-port-multiplier-aware-2x-sata-iii-6gbps-low-profile-pcie-20-host-adapter) connected to a 1x PCIe slot. I was thinking this was the bottleneck as im capping out at 250MB/s no matter if im using Raid 0, Raid 5 or Raid 10.

I tried connecting over usb 3.0 to make sure that its not the PCIe slot that is the bottle neck but im getting the same speeds.

Is this normal, is there anything i can check?

with 4x 2TB barracua 7200rpm drives I was expecting more like 500-600MBS


enter image description here RAID 5 - SATA

enter image description here RAID 10 - SATA

enter image description here RAID 10 - USB

enter image description here RAID 0 - USB enter image description here Copying from SSD to Raid 10 SATA


With 4x 2TB barracua 7200rpm drives your measured speed is excellent in RAID10.

Your expected values for RAID 0 in a best-case scenario, but still there is some clear limitation preventing your array to get more speed. You should of had 400MB/s at minimum.

Note that the SATA card you linked was not designed for RAID, therefore it may be limited.

Also, on USB 3 you will never hit specified speeds, there are many factors that can limit them. You should test RAID 0 with USB 3, though. You might get more speed.

If you want to use RAID 0, you should get a SATA adapter that actually supports 4 ports in any RAID configuration and you should have no limitation and make the RAID directly from the adapter, not from the OS. Otherwise, RAID 1 speed is fine. If you want to keep RAID 1, keep it as-is. You can't get more speed out of that one.

  • Thanks for the advise, Ill wipe the array again and test on USB three, if thats expected for RAID 10 I may end up using that so I have a backup of my virtual machines, the array is primarily used for that. Thanks – WraithNath Jan 19 '17 at 9:39
  • Yes, in RAID1 / 10 you get max double the speed of a single drive. But do the USB RAID 0 test, it would be interesting to see how much it can handle on your system. – Overmind Jan 19 '17 at 9:44
  • I have uploaded a test of Raid 0 on USB 3, seems a bit slower than SATA, CPU is at about 10% during the test. Just wanted to test for completeness – WraithNath Jan 19 '17 at 10:09
  • Just uploaded a pic copying from SSD to RAID 10 on sata, this is going at 472 MB so its certainly capable of faster speeds! – WraithNath Jan 19 '17 at 10:47
  • That can be cached writing. Use HD Tune to test read speeds (or even write speeds if the drives are empty). – Overmind Jan 19 '17 at 10:50

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