APFS available on Apple SSD in external enclosure?

[godrifle]

I have an Apple SSD that I pulled from a MacBook Air, in a Transcend USB3 enclosure. Works like a champ. Yet, when I install High Sierra, it doesn't format it as APFS. Although early versions of HS had an option in Disk Utility to convert the drive to APFS (and it consistently failed), in the newer releases the option is greyed out, even when booting from recovery.

Command line conversions resulted in a non-bootable disk as documented elsewhere. Nothing I tried would resolve the non-bootable condition.

Just wondering whether this is simply an unsupported combination of controller & SSD, or if anyone has further details they can share.
[doublepost=1503408553][/doublepost]Update: unmounting the disk first from recovery allows the conversion. However, after conversion is successful on reboot the system doesn't show the startup sequence. The activity light on the external enclosure continues to blink blue.

Looks like yet another reinstallation of High Sierra. :-/
[doublepost=1503409036][/doublepost]From recovery, if I choose the APFS volume with High Sierra on it as boot drive, I get the error "You can't change the startup disk to the selected disk. Running bless to place boot files failed."

 

[rumormiller]

I had the same problem, I submitted feedback with a workaround as follows:

• I have Sierra 10.12 installed on my internal 1TB Fusion Drive

• I installed High Sierra Beta onto an external SSD connected via USB 3.

• This SSD volume was Mac OS Extended (Journaled)

• I converted the SSD volume to APFS by booting into recovery mode cmd-r and using disk utility to do the conversion

• I tried to select the APFS SSD as the startup disk but the preference pane complained it could not bless the boot files or something similar

• On reboot holding down option, only the recovery partition for High Sierra and Sierra 10.12 (internal) would show

• I then booted into macOS Sierra on my internal Fusion Drive and ran first aid on the disk. It reported success.

• Then I tried to select the SSD as the startup disk again and the error message “building boot caches on boot helper partition failed”

• So I held down the OPTION KEY as I selected REBOOT and kept option held down until the boot up time disk chooser showed. This time High Sierra startup partition and the recovery partition both showed up. I was then able to boot into High Sierra fixing the issue.



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