On my iMac I use an external SSD as harddisk, connected with FireWire. I have updated from Sierra to High Sierra. The SSD is still formatted as HFS, extended journal.
I restarted afterwards in recovery mode to use the Disk Utility to convert to APFS, as it is a SSD drive. But i cannot get to convert as the command: "Convert to APFS" remains gray lined - and cannot be chosen.
How can I solve this problem.
iMac, iOS 10.3.3
use the erase function. Once you get to APFS then you should see a container and a volume besides the media. yes external SSD can be made APFS, I've completed plenty of them.
External drives, even SSD's do not convert to APFS.
As others have stated if your external drive is bootable you cannot convert to APFS. It is better to leave external drives as HFS journaled anyway to be more compatible.
And you don't have to erase it first either, see image above. You would need to erase it going from APFS back to HFS+, but not the other way around. Note, we're not talking about bootable drives here.
Well, after rereading the OP's original post, I'm not sure if the OP is talking about bootable drives or not.
Are you sure about that? I've used external drives, both SSD and mechanical with APFS formatting, easily done with Disk Utility.
120 GB SSD external:
I assumed the OP was talking about a bootable drive.
I think that you're right after re-reading his posting.
It's a habit of mine, possibly wrongly, to assume that portable drives are commonly bootable.
The part about booting from the Recovery partition was the clue.
yep, thanks. I misread that screen shot.
Thank you for your helpfull answers!
Yes this external drive is bootable - so I will leave it as it is - HFS journaled.
will converting external disks cause the user data to be erased?
Did you read this thread?
How to convert an external SSD drive from HFS to APFS
