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Model: iMac, 27 inch, Fusion Drive, 2017

Version: MacOS Monterey Beta (Version issues), MacOS Catalina (Version in bootable drive)

Notes:

  • I have a separate bootcamp Windows partition which works fine
  • Fully backed up to Time Machine
  • Entering the Time Machine volume without the Macintosh HD volume causes it to exit out

So recently, due to some crazy issues that were plaguing my Mac, (180% CPU usage, getting 5 fps, strange display colours, e.t.c.) I decided to reinstall MacOS.

I shut down the computer, held down Command + R, and selected Reinstall MacOS. The process was going fine, but then I was hit by a blank error, and I was prompted to select a volume to reinstall to. The selection was stuck however, and after 40 minutes and nothing happening, I decided to stop the reinstall.

But after restarting, and holding down Option, the Macintosh HD partition didn't show up. I created a Bootable Installer using a 32gb stick I had lying around. So I booted into the installer, and hit reinstall. The installer prompted me to select a volume, and as before, Macintosh HD was missing.

In its stead, there is volume disk0s2, a HDD with 490.02 GB of storage, and disk1s2, a SSD with 27.69 GB of storage, both which were parts of the Macintosh HD partition of the Fusion Drive.

So how can I rebuild Macintosh HD so that I can reinstall MacOS?

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS                         490.0 GB   disk0s2
   3:       Microsoft Basic Data BOOTCAMP                509.4 GB   disk0s3
   4:           Windows Recovery                         571.5 MB   disk0s4 

/dev/disk1 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *28.0 GB    disk1
   1:                        EFI EFI                     314.6 MB   disk1s1
   2:                 Apple_APFS                         27.7 GB    disk1s2

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  • Could you post to your question the entire output from diskutil list internal? Jan 2, 2022 at 11:04
  • /dev/disk0 (internal, physical) #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI EFI 209.7 MB disk0s1 2: Apple_APFS 490.0 GB disk0s2 3: Microsoft Basic Data BOOTCAMP 509.4 GB disk0s3 4: Windows Recovery 571.5 MB disk0s4
    – Vikram
    Jan 3, 2022 at 1:57
  • part 2: /dev/disk1 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *28.0 GB disk1 1: EFI EFI 314.6 MB disk1s1 2: Apple_APFS 27.7 GB disk1s2
    – Vikram
    Jan 3, 2022 at 1:58
  • Also I have found a potential solution: To use the diskutil resetFusion to reset the fusion drive a create a volume to install MacOS. However, this will delete bootcamp. My plan is to use this command, install MacOS, partition Fusion Drive, install Bootcamp on that partition, restore MacOS using Time Machine, and restore Windows using a System Image.
    – Vikram
    Jan 3, 2022 at 2:02

1 Answer 1

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I believe the following should work. I can not be sure, because apparently the output you posted from diskutil list internal shows damage.

diskutil apfs deleteContainer -force disk0s2 Temp1
diskutil apfs deleteContainer -force disk1s2 Temp2
diskutil apfs create disk0s2 disk1s2 "Macintosh HD"
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  • Yup. resetFusion works, and I have installed MacOS, updated to Monterey, and restored using Time Machine.
    – Vikram
    Jan 3, 2022 at 17:36

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