Create a RAID 10 on Mac OS (Monterey)
- July
- 31
11:27 pm Mac
I had four WD RED 4TB drives and wanted to get better performance out of them with a mirror but also wanted the ability to replace a drive if (when) one failed.
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Indications from online searching said I could create either a RAID 10 or 0-1. I'm not sure if one is better than the other. I went with the 10 configuration since I'm already familiar with that on my TrueNAS.
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Trying to do this from the Disk Utility always failed with an error message saying the RAID couldn't be created. The only type of array I was able to create out of two mirrored pairs of drives was a concatenated array. That still gave errors but appeared to have worked. But that's not going to give me any performance benefit.
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Instead, the solution is to do everything from the command line. So here we go....
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By the way, my disks are in an external cabinet attached via Thunderbolt 3.
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The four disks are disk2, disk5, disk6, and disk7 (use 'diskutil list' to find yours). Make sure you get the correct disks as they will be repartitioned and reformatted.
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Let's create the first set of mirrors from disk2 and disk5. I named the set vdev0.
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# diskutil createRAID mirror vdev0 JHFS+ disk2 disk5
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Now we'll create the second set of mirrors from disk6 and disk7.
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# diskutil createRAID mirror vdev1 JHFS+ disk6 disk7
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Now do a 'diskutil list' and find the disk numbers of the newly created mirrors. Mine were disk8 and disk10.
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Finally, create the striped set of mirrors. I named mine WDRED.
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# diskutil createRAID stripe WDRED JHFS+ disk8 disk10
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That's it. if you do a diskutil AppleRAID list you'll see the two mirrors and also the striped set which should now be mounted.
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