Screwed up 1TB Fusion drive 2017 iMac

fbx1989

macrumors newbie
Original poster
Aug 7, 2017
27
9
I was cleaning up the iMac (2017 27" 1 TB Fusion drive running Sierra) and somehow barfed the Fusion drive. I erased the partition (Macintosh HD). I tried to repartition the drive as 2 partitions and got never-ending beachball and had to shut down machine to get out.

Now the Fusion drive shows only 1 partition and it's half-size (about 512 GB).

When I try to repartition now the big blue circle is 1.03 TB in two sections, but the 2nd section DOES NOT show up in left hand pane of the Disk Utilities. Just the one drive as stated above.

Have tried this in Terminal from Internet Recovery (picked up from Apple Forum) But no joy--

N=Macintosh\ HD; for d in /dev/disk?; do o=`diskutil info $d`; [[ ! "$SSD" ]] && grep -lqw 'APPLE SSD' <<< "$o" && SSD=$d; [[ ! "$HDD" ]] && grep -lqw 'APPLE HDD' <<< "$o" && HDD=$d; [[ "$SSD" && "$HDD" ]] && break; done; diskutil cs create "$N" $SSD $HDD && diskutil cs createLV "$N" jhfs+ "$N" 100%

Had various troubles with booting but now have been able to install Sierra (from Internet Recovery) on what is shown as the 512 GB Macintosh HD drive.

Now I'm kind of lost and in need of guidance. This is a brand new machine and should not have any disk difficulties. If I could just nuke the drive and reformat it as a 1TB Fusion that would be great. Got plenty backups etc. No fear of losing data.

Much appreciate any help, advice, suggestions, etc.

fbx

PS Some discussion here
https://discussions.apple.com/message/32071183?ac_cid=op123456#32071183
 

Luxtrau

macrumors member
Jun 16, 2017
76
25
Germany
I'm not an expert, maybe you killed the one hidden drive for good? Once I had a fusion drive and the only advise I can give is "Don't choose FusionDrive". One of the drives was damaged and so the complete FusionDrive was unusable.
 

Weaselboy

Moderator
Staff member
Jan 23, 2005
30,456
10,263
California
I was cleaning up the iMac (2017 27" 1 TB Fusion drive running Sierra) and somehow barfed the Fusion drive. I erased the partition (Macintosh HD). I tried to repartition the drive as 2 partitions and got never-ending beachball and had to shut down machine to get out.
Run each of the two commands below in Terminal and tell us the output of each command. With that info we can tell you what to do next.

Code:
diskutil list

diiskutil cs list
 
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fbx1989

macrumors newbie
Original poster
Aug 7, 2017
27
9
Run each of the two commands below in Terminal and tell us the output of each command. With that info we can tell you what to do next.]

Thanks. I ran the two commands in Terminal and got these--
 
Last edited:

Weaselboy

Moderator
Staff member
Jan 23, 2005
30,456
10,263
California
Okay... we can work with this, but it will require starting over with erased drives.

Command-option-r back to Internet recovery and follow my instructions in posts #6 and #14 in this thread. That will bring back the Fusion drive at full size.

Then if you have a Time Machine backup, just attach it and click restore while still in Internet recovery.
 
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fbx1989

macrumors newbie
Original poster
Aug 7, 2017
27
9
Will do immediately.
[doublepost=1502131316][/doublepost]
Okay... we can work with this, but it will require starting over with erased drives.

Command-option-r back to Internet recovery and follow my instructions in posts #6 and #14 in this thread. That will bring back the Fusion drive at full size.

Then if you have a Time Machine backup, just attach it and click restore while still in Internet recovery.
OKAY did first step and got the following:

IMG_5504.jpg
IMG_5505.jpg
IMG_5506.jpg


It appears to have separated the SSD and the HDD but the HDD is back to proper size and the SSD is 28GB as advertised. What next? I guess I need to put the two drive s back together somehow?

Is that what message 14 in other thread is about?

Guessed that this instruction

"Okay... now quit Terminal and launch Disk Utility. Go to the erase tab and select the disk at the top left of the left column. Then select Mac OS Extended (Journaled) and apply that format. Then quit Disk Utility and click reinstall OS X at the top and what for the ~6GB OS to download and install. That should get you back in business."

applied to non-Fusion drives. So I did not try that yet.
 
Last edited:
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Weaselboy

Moderator
Staff member
Jan 23, 2005
30,456
10,263
California
It appears to have separated the SSD and the HDD but the HDD is back to proper size and the SSD is 28GB as advertised. What next? I guess I need to put the two drive s back together somehow?
You are doing fine... now you need to make the two physical drives into the Fusion drive. Just follow my instructions step by step here.
 
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fbx1989

macrumors newbie
Original poster
Aug 7, 2017
27
9
You are doing fine... now you need to make the two physical drives into the Fusion drive. Just follow my instructions step by step here.
Just to be certain, this line has "createVolume" pushed together. Is correct? Or should be "create Volume"

"diskutil cs createVolume DBFEB690-107B-4EA6-905B-2971D10F5B53 jhfs+ Fusion 100%"
 

fbx1989

macrumors newbie
Original poster
Aug 7, 2017
27
9
All one word is correct.
Sorry to be pesky, but I have no DBFEB690 in my string. Its just

87C26418-5FF5-49A3-A184-A13D0FEAC609

That sound right enough?

Never mind. I see it's the same number of digits in same places so I guess it's exactly as you said.
[doublepost=1502133480][/doublepost]Fabulous! Perfect! Extraordinary! Weaselboy to the Top! What can I do to thank you for this wonderful and clear and effective and correct correction of my screw up? 1000 thanks! I am thrilled and greatly relieved. Made my day. Never forget. All that stuff. Sir.
 

propower

macrumors 6502a
Jul 23, 2010
724
114
Man - I should have posted the problem when I did the exact same thing! Never could fix it. In the end I returned that unit to Apple with half the HDD missing!
 
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