trying to create RAID 1 volume called “Backup”

Discussion in 'OS X El Capitan (10.11)' started by mcburney, Jan 11, 2016.

  1. mcburney macrumors newbie


    Jan 11, 2016
    Hi All

    I'm trying to setup a mirror RAID on my new LaCie 2Big volume. I've partitioned the volume to two drives (I think) and I have typed in this into terminal:

    diskutil appleRAID create mirror Backup JHFS+ disk2s2 disk2s3

    but I get the following error message:

    Started RAID operation

    Unmounting proposed new member disk2s2

    Can't create a RAID set from multiple slices of a whole disk

    Error: -69886: Invalid request

    So my question is this - do I need to type something else into terminal or have I setup the volume correctly? I think it may be that I haven't got the two drives setup as two separate disks?

    Please see attached screenshot for how the LaCie looks when I type diskutil list in terminal


    Attached Files:

  2. KALLT macrumors 601

    Sep 23, 2008
    You are attempting to create a RAID from two partitions, not disks. That will not work. You have to enter the disk identifiers to create a RAID with two disks (basically “disk2” without the “s2”). When you type “diskutil list” you should see at least 3 disks: disk1 (which is your main drive), and disk2 and disk3 (which are your LaCie drives). If you only see the former two, that means that your drive is probably already set up as RAID.
  3. mcburney thread starter macrumors newbie


    Jan 11, 2016
    yes i only see the former two but disk2 showed as 6TB when it should be two 3TB disks (I can see them physiallcy as two disks in the aluminium case) so i tried creating a mirror RAID figuring this command in terminal would sort it out:
    distil appleRAID create mirror Backup JHFS+ disk2

    However, that seems to have created one 'external, physical' disk at 6TB and one 'external, virtual' disk at 6TB (see attached)

    I don't think that is correct - shouldn't the two disks be 3TB each?
    --- Post Merged, Jan 12, 2016 ---
    Ok, so i get it now - my drive is already preconfigured with a hardware RAID0 - i think i need to go back and see if I can change the RAID mode to RAID1 and then partition the disk drives - duh

    Attached Files:

  4. KALLT macrumors 601

    Sep 23, 2008
    Yes, you need to do undo the RAID0/Spanning to use both individual drives for a RAID1 setup. I highly advise checking the manual of your drive before proceeding. Maybe they even offer their own software.

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