Enabling RAID Mirrors Redux

When new versions of operating systems come out sometimes articles need to be updated. It’s always nice when someone else does the hard part. Recently, Ben Levy, an Apple Consultant from Los Angeles, did some work on an article I did awhile back. To quote Ben, the new procedure is to:

1. Boot from something other than your intended RAIDed boot drive, open Terminal and use diskutil list to identify the relevant disks and partitions.

2. diskutil appleRAID enable mirror disk0s2 – (assuming correctly identified slice, yours may be different) This command turns your primary disk into a RAID mirror without a mirror

3. Reboot back to your boot drive

4. diskutil checkRAID and diskutil list just so you know where and what everything is…

5. diskutil AppleRAID add member disk2 8014A446-E10D-4BC9-A199-67362E54FB7C – (assuming disk2 is in fact the drive you are adding) the UUID is the UUID of the RAID as discovered in checkRAID

6. diskutil checkRAID should now show it rebuilding the RAID. This could take hours. You can check on the progress again using the same command.

Thanks to Ben for the hard work. Now, I think it’s about time I wrapped this into a GUI app…


  • February 25, 2010 - 3:18 pm | Permalink


    The bit about needing the UUID of the RAID is just wrong. I did this the other day, just using device numbers “disk2″ and it worked great, just as the man page says.

    Evidently, there’s issues with this process, depending on whether the RAID is bootable, and whether you’re booted from the install CD or some other drive that can change the necessary parameters. Not to mention that the diskutil command is simply buggy at times.

    If you write a GUI for this, you better have some good insurance ;-)

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  • PFudd
    November 17, 2011 - 12:12 pm | Permalink

    Here’s instructions for 10.5.8. Boot from external drive, then:
    diskutil list
    diskutil enableRAID mirror disk0s2 (source partition)
    diskutil addToRAID member disk1s2 /Volumes/yourname
    watch diskutil listRAID (watch the progress go)

  • Jakob Peterhänsel
    February 13, 2012 - 7:40 am | Permalink

    DO NOT try this on a 10.7+ server!
    Your disk will be broken! Like, in, you will need to restore you system if you use RAID1. The Recovery Partition is NOT supported on mirrored RAID under 10.7+

    Apple’s Internet Recovery/Reinstall does also NOT work on a RAID1… :-(

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