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Possible to re-format APFS to HFS+?

macmesser

Contributor
Original poster
Aug 13, 2012
850
126
Long Island, NY USA
I formatted an SSD destined to become my new High Sierra boot disk as APFS, not realizing that HFS would have been fine. Is there any way I can re-format this drive to HFS+? They ought to issue a warning before formatting a drive as APFS, to the effect that Disk Util can re-format HFS as APFS but not APFS to HFS. Is there any command line way to completely erase APFS format and start clean?
 

Fishrrman

macrumors Core
Feb 20, 2009
20,422
7,244
OP wrote:
"Is there any command line way to completely erase APFS format and start clean?"

The problem with doing this is that it's going to DESTROY any data that's already on the drive.
You may already know this.

Really, if you have an APFS drive that you want to change to HFS+, the best way to "do it right" is to:
1. Back up any data on it to another drive. I recommend creating a bootable cloned backup using CarbonCopyCloner.
2. BOOT FROM the cloned backup drive
3. Open Disk Utility and ERASE the target drive to Mac OS extended with journaling enabled.
4. Quit Disk Utility and Open CCC.
5. Now, RE-CLONE the contents of the cloned backup BACK TO the original drive.
 
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macmesser

Contributor
Original poster
Aug 13, 2012
850
126
Long Island, NY USA
Disk Utility can reformat it to HFS+. Go to View > Show devices, make sure you select the top level of the drive in the left column, then Erase, choosing HFS Extended, Journaled as the format.

https://support.apple.com/en-us/HT208496
https://www.macobserver.com/tips/quick-tip/how-to-format-drive-guid/

Thanks!
OP wrote:
"Is there any command line way to completely erase APFS format and start clean?"

The problem with doing this is that it's going to DESTROY any data that's already on the drive.
You may already know this.

Really, if you have an APFS drive that you want to change to HFS+, the best way to "do it right" is to:
1. Back up any data on it to another drive. I recommend creating a bootable cloned backup using CarbonCopyCloner.
2. BOOT FROM the cloned backup drive
3. Open Disk Utility and ERASE the target drive to Mac OS extended with journaling enabled.
4. Quit Disk Utility and Open CCC.
5. Now, RE-CLONE the contents of the cloned backup BACK TO the original drive.

Thanks for reply. I have been using CCC and that is what I did, except I cloned to the different SSD with which I wish to swap the old one out. The original boot SSD had a verification problem which Disk Utility couldn't fix. The newly cloned system, on a larger SSD which I had reformatted to journaled Mac file system from APFS, did not have the verification problem according to Disk Utility and was bootable at first. I booted and restarted from it several times but it then started refusing to boot, displaying a "stop" symbol (circle with diagonal bar through) which stops the boot process. The drive itself tests good. Any idea what could be going on here? Could the identical systems, original and clone, be getting confused? BTW, when you refer to CCC bootable backup, do you mean an image file or actual volume?

Maybe I need to do a clean install, in which case I'll try it on the SSD that won't boot.
 
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holty

macrumors newbie
Feb 23, 2007
16
2
Townsville Australia
OP wrote:
"Is there any command line way to completely erase APFS format and start clean?"

The problem with doing this is that it's going to DESTROY any data that's already on the drive.
You may already know this.

Really, if you have an APFS drive that you want to change to HFS+, the best way to "do it right" is to:
1. Back up any data on it to another drive. I recommend creating a bootable cloned backup using CarbonCopyCloner.
2. BOOT FROM the cloned backup drive
3. Open Disk Utility and ERASE the target drive to Mac OS extended with journaling enabled.
4. Quit Disk Utility and Open CCC.
5. Now, RE-CLONE the contents of the cloned backup BACK TO the original drive.


Is this same process applicable to the OEM SSD inside my Late 2015 27inch iMac which was "auto converted" upon installing 10.14.0
 
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zorinlynx

macrumors 603
May 31, 2007
6,279
9,631
Florida, USA
APFS has proven itself as a reliable filesystem. Hundreds of millions of iOS devices are using it, and millions of Macs too. The only reason you would want to use HFS+ is compatibility with older MacOS versions, and Linux and other operating systems.

Just saying, this may be a pointless quest. :)
 
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linrey

macrumors newbie
Jun 13, 2007
29
10
Silicon Valley
It's not pointless if you have a fully functional Adobe Creative Suite running on a Sierra HFS drive and want to run it from the internal SSD in a Mac Mini 2014 that had the SSD that in it auto-converted to APFS with the High Sierra update.

The old Mini was perfectly happy with Sierra and it runs all of my 32-bit apps perfectly. I really NEED that Adobe software but am not in a position to subscribe to the cloud alternative. I currently have both 2014 and 2018 Minis running and switchable with a couple of button presses, so having the old Mini loaded with the software I want to use is my goal. But getting the internal APFS SSD running Mojave in the old Mini to erase/reformat, and load the older operating system is daunting. If it wasn't such a task to yank the SSD, I'd do it in a heartbeat.
 
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