Can't install High Sierra with fusion drive, AFPS error

[gallopinto]

Hi,

hopefully someone can help me out.
I have a 2013 iMac with a fusion drive. It's partioned, the SSD is the startup drive with MacOS on it and the HD is where all the data (photo's, video's, etc) is.

I wanted to a clean install and downloaded the installer, put it on a thumb drive, wipe the SSD and reinstall the whole thing.

There I made a big mistake, cause I formatted it to APFS instead of HFS+ thinking that as I was given the option I could formatted it to APFS. But I should have known that it's not supported yet. It didn't continue the install and now I'm stuck.

I can still boot to the OS High Sierra installer, but it keeps on hanging into the screen with the mouse and keyboard showing up asking for connection. The keyboard seems to work, but the mouse cannot pair for some reason. I hooked up and old school USB mouse and that didn't work either.

I can also boot to the Internet Recovery, and there the mouse works and all. But it says both the SSD and HD are corrupt and need to be wiped.

The thing is there's still some data on the HD that I'd like to keep. The most important ones I have backed up (documents, photos, etc), but not everything.

So the thing I would like is to keep the whole Data partition and reinstall High Sierra, but I don't really know an option from here besides wiping the drives with internet recovery and start all over.

Any ideas?

Thanks in advance!

 

[Mac Hammer Fan]

Stay away from APFS, especially on a Fusion drive. And it is not faster than HFS+ on my SSDs in my MacPro.
In a few months however, APFS will be perhaps much improved.
Re-initialize your Fusion drive under HFS+ format and restore a backup with Carbon Copy Cloner.
Try to boot from an external Sierra disk to backup additional files first.
Good luck.

 

[BLUEDOG314]

If the computer was not previously on High Sierra it did not get the firmware update needed to "see" APFS yet. If you use internet recovery to erase the SSD drive back to hfs+ then install High Sierra on it, it should automatically convert it to APFS and leave the HDD untouched.

 

[Fishrrman]

OP wrote:
"The thing is there's still some data on the HD that I'd like to keep. The most important ones I have backed up (documents, photos, etc), but not everything.
So the thing I would like is to keep the whole Data partition and reinstall High Sierra, but I don't really know an option from here besides wiping the drives with internet recovery and start all over."

Before going further, let's get something clear here.
You said "data partition".
Does that mean you have a partitioned drive?
If not, what DOES it mean?

If you keep your data on a separate partition (I do this myself), then, do this:
1. Get an external drive
2. Erase it to HFS+ with journaling enabled (if it's not that way already)
3. Download CarbonCopyCloner (FREE to download and use for 30 days)
4. Use CCC to clone the data partition to the external drive (you will now have an EXACT COPY of it)

NOW you can completely erase the internal drive back to HFS+ with journaling enabled and install a clean copy of the OS onto it.

If you have a bootable copy of the installer on a USB flash drive, you're already one step ahead in the game.

And a final bit of advice:
STAY AWAY from APFS for the time being.
Don't fall for the "I have to have the latest and greatest".
Use WHAT WORKS for you.

Even if the data isn't on its own partition, you can STILL connect an external drive, and then just use the finder to copy relevant folders to your external drive.
Then... start over.

 

[dianeoforegon]

I have an iMac late 2014 fusion drive. I de-fused (unlinked) so it is now two separate drives. I installed High Sierra on the SSD drive and it works great. I use the 1TB HHD drive for my Documents, Downloads, Movies, Music, Pictures. I keep very little on my Desktop. Most of the data on the SSD is Applications and User's Library. I have approx 80 GB available.

If you are interested see
https://www.lifewire.com/split-fusion-drive-apart-2260166
https://forums.macrumors.com/threads/disable-fusion-drive.1485175/page-2