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And recover/reconstruct the data (that is split in half) across two SSDs? I just haven't noticed enough real-world-usage improvement using RAID-0 (perhaps related question) and would like to use the 2nd SSD for something else. I do have a pre-RAID disk image from a couple of days ago.

In short, is there a straight-forward way to revert a RAID-0 set? Thank you.

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up vote 1 down vote accepted

If you break a RAID-0, all data on it is lost. To "recover" data from a RAID-0 you need to back it up to some other disk first, then break up the RAID, create new volumes on the single disks, and restor ethe data to the new volume(s).

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Can one restore RAID-0 from a Time Machine backup? – Blaz Sep 11 '12 at 5:52
Sure, as long as the backup doesn't reside on that same RAID-0. – Ansgar Wiechers Sep 11 '12 at 18:31

NO. Disk Utility can create RAID arrays but not de-construct them. However this can be accomplished via the Terminal application using the Command Line. LaCie Technical Support provided the procedure to me for one of their drives I am using:

DE-Construct a LaCie Little Big Disk RAID Array

(From LaCie Technical Support on May 29, 2014)

IMPORTANT NOTE: The procedure below involves the use of the Terminal program. This program, if used incorrectly, can cause data loss, or other problems. Ensure everything is typed precisely to avoid data loss.

Ensure an up to date backup exists prior to starting this process. It is important to ensure you do not have any other removable drives attached to the computer other than the one we are working with during this process.

  1. Open the program "Terminal". This is within the Utilities folder (MacHD --> Applications --> Utilities)

    In the terminal window, type:

    diskutil list

    Then press Enter. Ensure this is all lower-case, as everything is case-sensitive within Terminal.

    This command will return a list of all the attached drives on the computer by a unique hardware identifier. (e.g. disk1, disk1s1). At this point, you will need to determine the correct identifier for the drive we are working with.

  2. If you are having problems getting the volume to dismount in Disk Utility, you can use the following command:

    diskutil unmount force (identifier)

    This step is not necessary if the volume for the drive we're working with is already unmounted. In that case, proceed to the next step.

  3. One of the disk identifier entries may show the overall RAID set that was configured on the drives. If that is present, use the following command to remove this item:

    diskutil appleraid delete (identifier) 

    Again, if the RAID set is not visible in the listing shown in step 1, then proceed to the next step.

  4. The following command will completely eradicate any remaining header information on the individual disks. This command would need to be done for each disk in the array:

    diskutil zerodisk (identifier) 

    Please be very careful when running this command. This will fully wipe all data from the target drive(s). This should, however, clear off the inaccurate header indication on the drive that is incorrectly telling Disk Utility the drive is "broken".

    This process will start a long zero-out procedure on the drive. If you wish to test the hardware integrity of the drive mechanism, you can let this process complete to 100%. If this completes without errors, then we know the hardware of the drive mechanism is completely healthy. This will take several hours to finish on most systems.

    If you do not wish to wait, then you can usually interrupt this process (Control + C will abort this) after a minute or two. The important header information is one of the first things to be erased by this process, so even if interrupted, this command should still correct the problem.

  5. After everything is finished, you should be able to exit Terminal, and go back into the Disk Utility Application to re-configure the RAID array on the device.

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