Restoring partitions after bootcamping failure...

Hi all,

I'm a new Mac user so please bear with me...

I just bought a late 2013 iMac with High Sierra preloaded, a 120GB SSD and a 1TB HDD.
I was keen to dual boot Windows 10 so i made a thumbdrive iso and followed the bootcamp instructions.
I made a second partition for windows on the SSD (alongside OSX) but had problems with the Windows installer saying "We couldn't create a new partition or locate an existing one". I tried removing any extra USBs etc then found some advice which recommended deleting the "Bootcamp" partition and creating it again which I tried without success. Loading back into OSX and bootcamp was now saying that the SSD had partitions created by a different utility (windows I guess) and it couldn't repartition. I went into Disk Utility and tried erasing the partition/merging but the minus sign is greyed out. I now have a partition I can't get rid of!
The Mac is basically unused so if its easiest to do some kind of hard reset then I'm happy to do that. If anyone could walk me through restoring the partitions and/or dual loading windows it'd be much appreciated. I'm a bit new to this level of work so detail would be appreciated. Thanks in advance.

Your best bet would be to create a USB macOS installer. Follow these instructions, https://support.apple.com/en-us/HT201372. Be sure to have all your data saved on a separate drive.

Suggest you do not partition the PCI-e drive as it is too small to run your OS X operating system, applications and Bootcamp.

Does his iMac have a Fusion drive or two separate drives? I suspect it's a Fusion Drive made up of a 120 GB SSD and 1 TB spinner. That's likely the reason why the partitioning failed. He should have created the Windows partition on the 1 TB spinner if that's the case. Now, the drive is totally screwed up and will have to be erased and macOS reinstalled. Apple has instructions for doing all that on a Fusion Drive.

harryb2448 said:

Suggest you do not partition the PCI-e drive as it is too small to run your OS X operating system, applications and Bootcamp.

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+1!! As harry says, that's cramping things too tight on a 120GB drive and it would probably soon choke itself with a slow death.

Does his iMac have a Fusion drive or two separate drives? I suspect it's a Fusion Drive made up of a 120 GB SSD and 1 TB spinner.

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The Fusion drive was an BTO option with those Macs I believe.




- Patrick
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The Fusion drive was an BTO option with those Macs I believe.

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Yes that's true. I remember when I purchased my 2013 iMac the Fusion drive was an extra option that cost quite a bit more. I went with the straight 1 TB spinner instead. The 2013 models did not come pre-equipped with the extra bracket for a second drive installation. That had to be ordered from OWC. It is possible that his iMac has two separate drives but until we hear back from the OP, I'm assuming he has a Fusion drive that is now totally screwed up.

Late 2013 iMacs came with option of 1,2 or 3TB Fusion drives with 128GB PCI-e drive.

harryb2448 said:

Late 2013 iMacs came with option of 1,2 or 3TB Fusion drives with 128GB PCI-e drive.

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Just curious as I've never had to need to go delving into such a Mac, but do the SSD and HDD drives show as separate volumes and with an option to partition or choice of which to do any installs on???

I always understood that a Fusion drive just showed up as a single volume.




- Patrick
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The drive shows up as two in Disk Utility, but in fact is fused together as one. Which is why it's called a Fusion drive. I believe the mounted drive (Macintosh HD) shows up on the desktop as one. I can well understand why that would confuse someone who was new to Macs and especially if they never heard of a Fusion drive. No doubt that's why the OP attempted to create a Windows partition on the SSD portian of the drive.

The drive shows up as two in Disk Utility,
… … …
I believe the mounted drive (Macintosh HD) shows up on the desktop as one. I can well understand why that would confuse someone

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Thanks for the clarification and info Charles.

The closest I ever came to working with such a thing was with a "hybrid" drive I think they were called that we installed in my son's MBPro many years ago. It just showed as a single HDD as I recall.




- Patrick
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Thanks guys. It shows up as two, not sure how to determine if it is a hybrid or not. Not even entirely sure what that means. I guess I'll just reinstall OSX and try bootcamp on the HDD.

Hmmm, I followed the instructions at https://support.apple.com/en-us/HT201372 and downloaded High Sierra again from the app store. When I installed it it offered me both partitions to load it on to. I decided to choose the 'windows' one I had created in the hope that the system would reformat it and bring it back into the Mac fold. Everything installed ok but I still have 2 separate partitions on my SSD that don't want to seem to merge. I tried running bootcamp to see if I could reformat into one again but that option is greyed out. Any further suggestions?

Hmmm, I followed the instructions at https://support.apple.com/en-us/HT201372 and downloaded High Sierra again from the app store.
…I tried running bootcamp to see if I could reformat into one again but that option is greyed out. Any further suggestions?

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I dare say, chscag's comment above is now a bit of an understatement, sorry:

I'm assuming he has a Fusion drive that is now totally screwed up.

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That is now possibly compounded by Apples HS and likely formatting the SSD as APFS. But I'm not sure.

As "a new Mac user" and for some constructive Mac advice, I'd suggest it may be best if you get some good Apple tech's help even if it's done commercially and get that Mac sorted out properly, otherwise this thread will probably be going on and on for ages.




- Patrick
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The idea of creating a bootable USB installer for High Sierra suggested by ferrarr in Post#2 was to erase the entire drive thus removing the partitions and creating a single drive albeit a fusion drive. tig5, you have downloaded the installer and run it as per the usual manner but unlike the bootable installer it cannot make changes to the structure of the HD because it is running on the HD. A HD cannot reformat itself because the process requires the HD to be unmounted then erased.
So you need to create another source to boot from. This requires you creating a bootable (meaning it can run your computer) installer from the HS installer you downloaded from the App store. For this you need a third party app called Diskmaker X.
If this all sounds a bit complex by all means seek help from an Apple tech.

The process is; Download the High Sierra installer, you may have to do this again because I think it erases itself after you use it.
Download Dismaker X for High Sierra from here; http://diskmakerx.com/
Plug in a USB thumb drive of at least 8Gb, 10Gb would be better.
Run Diskmaker X, it will offer to create a bootable installer from your HS installer. It will erase the USB drive completely and create the installer.
When complete you can restart the computer holding the option key. You should get an option to boot from the USB.
Once booted you can use Disk Utility to erase you internal HD and then install a fresh copy of HS.
This will return your internal HD to one partition running HS.
You can then restart and select your Macintosh HD as the startup disk.
Put the USB aside as it may be very handy in the future for repairs or diagnosis.

Once booted you can use Disk Utility to erase you internal HD and then install a fresh copy of HS.
This will return your internal HD to one partition running HS.

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Was there not some discussion recently of Disk Utility's inability to delete ALL partitions if a Windows partition had been setup or established???

I'm also not sure if that will be of any concern in this case. And maybe the Fusion drive makes things even more complicated.





- Patrick
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Youre right Patric but I cant remember the instance. Non the less I did this two weeks ago for a nephew who had purchased a second hand 2013 MBP that also had been partitioned for Bootcamp, absolutely no problems encountered.
I am another user who's HD is partitioned for Windows 10 with bootcamp. I noticed about a month ago that Bootcamp Assistant is now unable to remove that partition as per current instructions under High Sierra. I just get a, "The startup disk cannot be partitioned or restored to a single partition." message.
I did post about this at the time. Looks like HS broke BA?

I noticed about a month ago that Bootcamp Assistant is now unable to remove that partition as per current instructions under High Sierra. I just get a, "The startup disk cannot be partitioned or restored to a single partition." message.

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It seems Apple posted a kb article about that: Published Date: May 13, 2016
Boot Camp: Partition alert message when using Boot Camp Assistant
https://support.apple.com/en-ca/HT203913

Is Disk Utility.app not able to completely erase all partitions???




- Patrick
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But it doesn't actually remove the partition. The storage us not returned to the HD.

No luck so far. When I access disk utility while booting from the USB I can see my HDD and 2 other storage devices named UNKNOWN. It appears I can erase, delete, reformat etc but I can't get them back into one. It seems I can't even change the size of them. If I delete both volumes they reappear as containers when I open disk utility again. Any other ideas would be much appreciated.