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I'm using a hardware HP RAID controller. My server came with one 250GB drive. I purchased three additional 250GB drives with the intent of having one as a cold-spare.

I put the two additional drives in the server and powered it up. I went into the BIOS, enabled the RAID controller, then rebooted. It brought me to the HP raid controller setup. I went in and deleted the three pre-existing arrays (which were just three drives operating independently of each other). I then selected the array configuration option, selected all three drives together, and told it to initialize. It did its thing, then I went into "create array" and again selected all three drives. It presents me with a dialog asking what kind of RAID that I want to set up, but the problem is that it doesn't present RAID 5 as an option. All I can choose is 0, 1, and 10.

I know RAID 5 is possible with 3 drives, so what gives? I've never set up a RAID array before so if there is something obvious I'm missing here don't hesitate to tell me...

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Maybe the RAID controller doesn't support RAID 5. –  Amuck Sep 17 '09 at 20:37
    
What raid controller is it? (model/part number) –  Zoredache Sep 17 '09 at 20:48
    
@Zoredache - Intel 82801 –  DWilliams Sep 17 '09 at 21:08
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2 Answers

up vote 1 down vote accepted

Your RAID controller doesn't support RAID 5.

As others have said and you have witnessed by "All I can choose is 0, 1, and 10." You'll need a different controller that supports RAID 5. You'll need to get with your VAR or HP and find one compatible with your server model.

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Ugh what's the reasoning behind shipping a RAID controller that doesn't support what is most likely the most common RAID configuration in history? Oh well, there's nothing stopping me from using Linux software RAID I guess... –  DWilliams Sep 17 '09 at 21:05
    
I wouldn't really call the ICH a raid controller, it is just a hard drive controller with fakeraid features. I believe I saw some benchmarks somewhere that showed Linux software RAID performing better then the ICH anyway. –  Zoredache Sep 17 '09 at 21:52
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It's possible that your RAID controller does not support RAID 5. Sometimes they will be a 'light' model that only supports 0/1/10 until it's upgraded either with a license or hardware key.

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