tinyapps.org / blog

Carbon Copy Cloner and SuperDuper! ignore EFI partitions #

When making a bootable clone with Carbon Copy Cloner or SuperDuper!, EFI partitions are skipped, since they aren't needed for macOS boot disks:

Though modern Macs support ... EFI booting in order to maintain compatibility with running non-Apple operating system[s] on their hardware, they do NOT need the EFI partition in order to boot [m]acOS. Because of this, the disk clone utilities do not copy the contents of the secondary EFI partition from one drive to another when doing their job.

However, this is problematic when cloning boot disks like the one produced by Ben Sova's Patched-Sur, which depend on the EFI partition for critical functionality.

Here's how to clone the EFI partition as well:

1. Partition (GUID) and format (HFS+) the target disk

2. Use Carbon Copy Cloner to clone the source disk to the target disk

3. Mount the source and target EFI partitions

   % diskutil list
   ...
   /dev/disk2 (external, physical):
      #:                       TYPE NAME                    SIZE       IDENTIFIER
      0:      GUID_partition_scheme                        *126.7 GB   disk2
      1:                        EFI ⁨EFI⁩                     209.7 MB   disk2s1
      2:                  Apple_HFS ⁨Install macOS Big Sur⁩   126.4 GB   disk2s2
   
   /dev/disk3 (external, physical):
      #:                       TYPE NAME                    SIZE       IDENTIFIER
      0:      GUID_partition_scheme                        *61.5 GB    disk3
      1:                        EFI ⁨EFI⁩                     209.7 MB   disk3s1
      2:                  Apple_HFS ⁨SanDisk                 61.2 GB    disk3s2
   % sudo diskutil mount disk2s1
   Volume EFI on disk2s1 mounted
   % sudo diskutil mount disk3s1
   Volume EFI on disk3s1 mounted

4. Copy the EFI folder from the source disk's EFI partition to the target disk's empty EFI partition via Finder or Terminal

Notes

• /bin was visible on the source disk but hidden on the target disk; used chflags nohidden /path/to/bin to unhide.

• EFI-Agent offers a simple GUI for mounting and unmounting EFI partitions (among many other features).

• EFIClone is a bash script meant to be launched by Carbon Copy Cloner or SuperDuper! after cloning in order to include any EFI partition; did not work under Big Sur in my limited testing.

• Rob Griffiths recommends EFI Mounter in his Frankenmac 2017: How to back up a hackintosh.

Sources

• How to mount EFI from command line (Terminal)

• jaymonkey's answer to Does Carbon Copy Cloner Copy the EFI Partition?

/mac | Apr 26, 2021

Subscribe or visit the archives.