RAID Mirror - Slice/Spare

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RAID Mirror - Slice/Spare

Hello Everyone,

We just bought an Xserve with two hard drives. The plan was to configure them as a RAID mirror.

I was able to create the RAID but it didn't give me the option to use one as "Spare" they both had to be "Slice". If I chose Spare then the configure button would go away.

The Xserve is going to be used as a web server. The goal is if one drive fails then the other kicks in and the server keeps running as if nothing happened. Will it work with the RAID this way?

Mac OS X (10.4.9)

Posted on Apr 12, 2007 5:10 PM

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Answer 1

Camelot

Level 9

58,581 points

Apr 12, 2007 5:35 PM in response to iPhrankie

You can't create a spare disk with just two drives.

Any RAID requires at least two drives (some RAID levels require 3 or more).

In the case of a Mirror (which is what you want), yout two drives have to be part of the mirror. You don't have an option for a spare.

A two-drive mirror is what you want, though. If one of the drives fails then the system will keep running off the other one until you get to replace the failed drive.

To have a spare you'd need three drives - two drives that are mirrored, plus a spare.

The spare disk would only be beneficial in that it would allow the OS to automatically start to rebuild the array as soon as one disk failed. It's OK to run without a spare, you just have to be aware that you have no redundancy until a failed disk is replaced.

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Answer 2

iPhrankie Author

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Apr 12, 2007 6:15 PM in response to Camelot

Thank you!

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