Linux: Expected RAID-0 Performance

My PC runs Linux Centos 6.4, and I have an ASUS SaberTooth systemboard with 6 SATA ports. I'm considering purchasing 4 3-TB Seagate Hard Derives and then creating a 1-TB partition on each drive and configuring that as a 4-TB RAID-0. That data will be used for video editing, so I don't care too much if one drive fails and I lose all data stored there at that time.

My question is this: what can I expect the read and write performance to be for very large files? Since this is for video capture and video editing, the files are huge and basically accessed in sequential order.

If a single Seagate 3-TB drive can deliver 160 MB/sec, then the largest possible speed for a 4-disk RAID would be 640 MB/sec. In practice, how close to that will I achieve if I simply connect the drives to the on-board SATA ports, as well if I purchased a RAID card (which one?)?

Thank you.
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  1. In practice, the limiting factor will be the storage controller's IO system bus bandwidth or internal bandwidth. I would expect R/W speeds closer to 350 MBps for 4 x 3TB WD Black, possibly up to 400.
  2. How would I determine the "storage controller's IO system bus bandwidth or internal bandwidth" for an Asus x58 SaberTooth system board? By the way, these would be Seagate drives.

    Would it be faster with a RAID card?
  3. Best answer
    your x58 sabertooth has 6 Intel sata2 ports and 2 Marvel sata3 ports. You cant raid across the different controllers so the 4 drives will need to be on the sata2 ports not that it will hinder mechanical drives much at all, so you should see above 550mb/s sequential reads with a peak of about 800. Write will be a tad slower naturally.

    As for getting a raid card, raid 0 does not use much cpu power as there is no parity information to calculate, I believe you will see negligible improvements thanks to Intel excellent engineering of its sata ports.
  4. I concur with the speed estimates. However, with Linux MD (software) RAID, you can create RAID arrays across multiple/different disk controllers. I recommend not using a RAID card and using only Linux software RAID instead. (You should also be using LVM, which I expect you are, on top of the RAID array.)

    I created a 4-disk RAID-10 array on my server (which will give you 50% of your total disk space, or a total of 6 TB in your case, that will be usable -- speed + redundancy). I'm seeing 3.3x speed increase over a single disk (r/w average). You can use 'palimpsest' to speed-test your disks & arrays.
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