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I have 4 2TB drives. I want to create a 4TB RAID 1 array.

I select the 4 drives in the RAID BIOS, and try to create an array, but my only options are RAID 0, RAID 5, and RAID 10. This controller is supposed to support 1, 6 JBOD...

I know I must be missing something.

Please help.

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Are the drives identical? –  Fergus Dec 21 '10 at 1:22
    
Yes, they are identical. –  brennanag Dec 21 '10 at 1:23
    
RAID 10 provides the same protection level as RAID 1, but the striping improves performance (well it should at any rate). Assuming it is a stripe of mirrors, which it should be. –  Helvick Dec 21 '10 at 1:27
    
Sorry for the basic question; did you enable the drive configuration, “Configure SATA As” > RAID in the Bios (assuming you have American Megatrends or Phoenix Technologies –  Fergus Dec 21 '10 at 1:27
    
The drives don't show up in the BIOS because they are attached to the 3Ware controller. I'm ignoring the controller and doing software raid instead. I hope. –  brennanag Dec 21 '10 at 23:45
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3 Answers

RAID1 can only have two drives on that controller. It does not support multiple copy mirrors. You'd have 1 single 2TB drive and 3 copies of it... If that's really what you want you'll have to use software RAID of some kind.

If you actually want a 4TB logical drive with the other 2 drives used as mirrors of the first two, that's RAID10.

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Good point..... –  Fergus Dec 21 '10 at 1:28
    
When I try to build a RAID10, it's 1.99 TB, not 4TB. –  brennanag Dec 21 '10 at 1:55
    
Also, when I select two drives and mirror them, it's saying the array will be just over 1TB, instead of close to 2TB. I must be just missing something so obvious here... –  brennanag Dec 21 '10 at 1:59
    
Is there an option to allow greater than 2TB volumes? If you have a volume larger than 2TB and you're trying to partition it you'll also have to use GPT instead of MBR partition tables. Depending on your OS it may not support booting off a GPT partition. –  3dinfluence Dec 21 '10 at 5:03
    
Might be an issue with the drives your using, try contacting 3Ware and see if they know of any issues with the particular brand/model of drives your using. –  Chris S Dec 21 '10 at 13:46
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The 9650SE 8LPML (8-port) manual says you need a minumum of 5 drives for RAID 6. You mentioned you have a 0650SE 4LPML card, which makes me suspect you only have 4 ports. If the card lets you add a second one like it and interconnect them, you could then do RAID 6 with the addition of enough drives to do so.

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Some RAID controllers only support RAID1 with 2 drives. Others will let you make a 4 way mirror. What happens if you try to make a RAID1 out of 2 of the drives?

RAID10 should result in close to what you're looking for. If you're just looking for a mirror.

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