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Screwed up 1TB Fusion drive 2017 iMac

fbx1989

fbx1989

macrumors member
Original poster
Aug 7, 2017
36
17
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
 
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.
 
fbx1989 said:
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.
Click to expand...
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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Weaselboy said:
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--
Click to expand...
 
Last edited:
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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Will do immediately.
[doublepost=1502131316][/doublepost]
Weaselboy said:
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.
Click to expand...

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 said:
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.
Click to expand...

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%"
 
Weaselboy said:
All one word is correct.
Click to expand...
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.
 
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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!
 
Weaselboy said:
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.
Click to expand...
Dear Weaselboy,
I noticed your posts regarding locked recovery discs. I’m a total newb. I turned on the Mac, it starts in recovery, I go to reinstall as nothing else seems to go anywhere. Then I get recovery HD is locked. I tried to follow your advice, but can’t find any mention of terminal in utilities. It only starts in recovery mode. Bizarre considering I closed down last night without worries. My assignment is due and I’m in up the creek. Any gentle advice is welcomed.
 

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Try holding command-option-r when you boot to get to Internet recovery, then start Disk Utility and tell me what you see.

If things were working fine yesterday, and you did not change anything, then this just happened all on its own I fear you have a failed drive.
 
Weaselboy said:
Try holding command-option-r when you boot to get to Internet recovery, then start Disk Utility and tell me what you see.

If things were working fine yesterday, and you did not change anything, then this just happened all on its own I fear you have a failed drive.
Click to expand...
Ok
 
Weaselboy said:
Try holding command-option-r when you boot to get to Internet recovery, then start Disk Utility and tell me what you see.

If things were working fine yesterday, and you did not change anything, then this just happened all on its own I fear you have a failed drive.
Click to expand...
Hey! Thanks so much. I held down command-option-r and got these images alternating and no mouse movement.
 

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I think that is just walking you through pairing up your mouse. Can you connect the mouse and continue.

After command-option-r did you get the spinning grey globe while the recovery utility was downloading?
 
Annoyednewb said:
Hey! Thanks so much. I held down command-option-r and got these images alternating and no mouse movement.
Click to expand...
Weaselboy said:
I think that is just walking you through pairing up your mouse. Can you connect the mouse and continue.

After command-option-r did you get the spinning grey globe while the recovery utility was downloading?
Click to expand...
Hey!
This is what I come to after selecting “English” as a language.
I see Terminal now.
Thx for hand hold.
 

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Now open Disk Utility and let's see if the drive is visible there.

If it is, open Terminal and run the command below then tell me the output.

Code: 
diskutil list
 
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