HFS+ from APFS

[sfphoto]

I read that 10.13/10.14 (as upgrades from older MacOS) installation re-writes the machine firmware and changes the file system to APFS from HFS+.

If I want to revert back to an older macOS which I have an installer for - will the installer revert the machine firmware?

OR

Can I simply erase with DidkUtility as Extended Journaled and then Clone my external backup of the older MacOS with CCC to the former APFS drive.

The APFS drive is an SSD.

 

[chrfr]

The firmware isn’t directly related to the APFS conversion, and you can always reformat back to HFS+ and restore or install an older operating system.

 

[sfphoto]

Thanks for the reply, I did:
Can I simply erase with DidkUtility as Extended Journaled and then Clone my external backup of the older MacOS with CCC to the former APFS drive.
And it worked fine.

 

[CoastalOR]

Thanks for the reply, I did:
Can I simply erase with DidkUtility as Extended Journaled and then Clone my external backup of the older MacOS with CCC to the former APFS drive.
And it worked fine.

The Disk Utility you use needs to be from High Sierra or Mojave to properly recognize a APFS system and be able reformat to Mac OS Extended (journaled) (HFS+).

The way I would do it is:
1. Make a USB installer for your older OS. Test the USB installer by booting from it (hold the Option key at startup for the Startup Manager and select the USB Installer).
2. Make sure you have a recent backup of your current system.
3. Make a USB installer for High Sierra or Mojave. Boot from it. Launch Disk Utility from the installer Mac Utilities window. Make sure you set the View to "Show all devices" and select the very top (1st) level drive name. Erase (format) to Mac OS Extended (journaled). Shut down.
4. Connect the older OS USB installer. Boot from it. Install the older OS.
5. Migrate your preferences, data, and third party Apps from your CCC backup using the Migration Assistant app in the Utilities folder.

CAUTION: Be aware the older OS Photos and iTunes will probably not be able to read the Photos and iTunes database that were modified by the newer app versions in Mojave.

 

[sfphoto]

Thanks all for the responses.

I started the machine (2013 MacBook w/ 10.14) from an external running 10.9 and erased the MBA internal SSD to HFS+

Using Terminal command diskutil list - now showed the SSD was HFS+

I then cloned a 10.12 clone from another connected external (clone was from another MacBook)

Success.