APFS Volume not erasing / converting to MacOS Extended

Discussion in 'macOS High Sierra (10.13)' started by lordspur89, Mar 31, 2018.

  1. lordspur89 macrumors newbie


    Sep 30, 2015

    So long story short, I tried the beta for 10.13, and having a fusion drive converted to APFS I have been hoping for an update to fix it.

    Clearly thats not coming or is a far way off so I wanted to run a clean install of the OS (I followed the apple guide and have this on a USB to install from).

    Problem is, when I try to install it says the internal drive I want to install it to is locked. I looked at disk utility to convert/erase but my only option is to reformat/erase this to APFS which does not help.

    Do any of you know what I might be doing wrong here/how to fix it?

    Many thinks in advance
  2. Fishrrman macrumors P6


    Feb 20, 2009
    First thing to check:
    With disk utility open, go to the "view" menu.
    Do you have the option to "show devices" (not just "volumes") selected?
    If not, select it.
    You want to be operating on the physical drive itself, NOT on any volumes on that drive.

    Next thing:
    I've read reports from others about the failure of disk utility (the version that comes with High Sierra) to erase the internal drive back to HFS+.

    Here's something from my archives (thanks to the original poster):

    Is the Mac booted from the internal recovery and you cant erase the drive? If so you need to boot it from external clone or install media (hard drive, memory stick etc.) and then you should be able to erase the drive.

    If you don't have a clone or install media use these instructions: http://macworld.com/article/3204672...otable-macos-high-sierra-installer-drive.html

    While you could try Internet recovery (Command-Option-R) it isn't very reliable in my experience and I prefer bootable installer.

    Also make sure you have made a backup before trying this, you wouldn't be the first one who would accidentally erase the wrong drive...

    If you want to just repartition it for APFS you could run
    "diskutil unmountdisk disk0"

    with disk0 being the internal physical storage, then run
    "diskutil erasedisk apfs "Macintosh HD" disk0".

    Hope this is of some help.
  3. dianeoforegon macrumors 6502a


    Apr 26, 2011
    You DO NOT convert a fusion iMac to APFS! APFS is not supported on fusion Macs.

    First backup your data to a clone backup.
    Boot from the Recovery Drive then select to erase the drive and convert back to HFS+. (you might have some trouble if you don't also delete the container)
    Most likely you will have to do Internet Recovery to install the original version of OS X that came on your Mac. Then you can upgrade to Sierra.

    APFS Fusion revert from APFS to HFS+

    Download Sierra

    To downgrade macOS, read Revert your Mac to a previous macOS version - Apple Support.

    You can after erasing the drive, defuse the drive and install High Sierra on the SSD drive (the installer will auto convert to APFS. Keep your Documents, Downloads, Movies, Music, Pictures on the HDD rotational drive (formatted HFS+). Remove the default folders from the sidebar in a Finder window and drag in the folders you created on the HDD drive. In Time Machine under Privacy, remove the HDD drive so Time Machine will also backup this volume.

    How to Delete or Split Your Mac's Fusion Drive

    Disable Fusion Drive | Page 2 | MacRumors Forums

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