Same 4 hard drives, but only 2 support APFS

In 2015 I purchased four of the WDBU6Y0020BBK: https:// (WD ELEMENTS PORTABLE)

After upgrading to Apple’s High Sierra OS today I attempted to reformat the drives so that they use APFS instead of Mac Extended OS. To my surprise, while two of the drives allow me to reformat them to APFS, the other two drives do not.


I have triple checked that each of these four drives are indeed the exact same model of portable hard drive. This situation has left me scratching my head about why identical hard drives do not support the same file systems.

Can anyone help me understand whether it’s possible to fix this problem and get all four drives over to APFS?

UPDATE: 9/29/17 - I spoke with Apple Support about this issue and have a Genius Bar appointment scheduled for 10/05. In addition to the formatting problem, I’m finding that files larger than 100MB take a long time to open. First, several seconds elapse between double clicking a file and seeing a File Vault window appear which says “Verifying [filename]” with a loading bar underneath. Once the file has been verified (takes about 30 seconds) the file will open, but will not function smoothly. For example, if the file is a movie, the video playback will be laggy and stuttering.

Unless I’ve missed something, the surprising thing is two of your drives that DID get reformatted as APFS. The released version of High Sierra supports APFS only on Solid State drives, not HDD. See, for example, this Apple support document:

I believe that earlier beta releases of High Sierra supported APFS on HDDs, but that support was removed in the final release. I’m afraid this doesn’t really answer your question, but it certainly makes the situation even more confusing. :slight_smile:

Hey jrock91,

No worries, I appreciate your reply! That article is a bit confusing because while it says traditional hard disk drives are not automatically upgraded to APFS when installing High Sierra, the article does not make it clear whether hard disk drives are able to upgrade manually. I will continue searching for help and will post here if I find a solution.