How can I delete a non-existant Windows-partition I saw after restart-up /option key?

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How can I delete a non-existant Windows-partition I saw after restart-up /option key?

Long ago (in 2017) I started to prepare a Bootcamp/Windows partition on my iMac, but never finished the process. Instead I bought Parallels, and installed it on a MBP portable (is working fine).

The 68GB partition always was empty, and recently I succeeded in erasing/clearing it (no partition left). I did not use Bootcamp to get rid of it - well because there was no Windows at all . .

However when I today restarted with /option key, I saw the option of a Windows startup. [It should not be there] I did not choose the option. .

How can I get rid of this 'ghost'?

Can I go ahead with Disk Utility/erase (I have a Timemachine copy ready; and I have a CCC clone) or is that also dangerous?

I must say that the TM backup is 159GB; the clone is 164GB (11GB 'system'); and the original content on the Fusion is 413GB. Howcome that difference?

Appologies for being stupid :-(

iMac 21.5″ 4K, macOS 10.15

Posted on Dec 10, 2020 8:06 AM

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Answer 1

Loner T

Level 9

59,536 points

Dec 11, 2020 1:54 PM in response to alberti-nl

You do not need to use Recovery. If you removed the Microsoft directory and reboot, you should no longer have EFI Boot in your Option/Alt selection.

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Answer 2

Loner T

Level 9

59,536 points

Dec 11, 2020 7:54 AM in response to alberti-nl

Good to see the Fusion drive show full capacity. The 28Gb is a smaller drive, and does not significantly change the Fusion drive size. Once you boot from the internal disk, mount both EFI partitions (from the 28Gb disk and the 1TB disk) and we can then check.

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Answer 3

alberti-nl Author

Level 1

36 points

Dec 10, 2020 12:19 PM in response to Loner T

Thanks LonerT,

and of course there is no way to get that away (without a degree in Terminal/Linux . . )

So the only thing to do is a complete wipe/erase, reinstall Catalina and then use the Timemachine?

Can that be done in one series of 'steps' via restart/command/R?

with `disk Utility, erase Macintosh HD = erase volume. repeat for Macintosh HD Data.
once finished, I stay in the startup screen that allows me now to install Catalina.
Select Macintosh HD [the small part of the Fusion Drive]
Enter user (my own)
Select backup- from Time machine. (luckily I have it on an SSD )
cross the fingers and wait 2 hours . . .

ps. I already have the Installer downloaded; does it help me?

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Answer 4

alberti-nl Author

Level 1

36 points

Dec 11, 2020 6:42 AM in response to Loner T

Thanks for puzzling me :-)

I am running from external clone right now & Disk Utility says:

The container Internal Disk is 933,7 GB [Mac HD 11,32 GB; Mac HD data 404,58; NOT ACTIVATED 7,27GB; Available 510,54 + on the volume data it says "other volumes" 18,58GB].
Note, The External Thunderbolt NVMe - disk0s3 - is 1,07 TB [system includes VM] -

So that 90GB could be old non existant 'destined for windows made by Bootcamp' partition I cleared by first formatting it HFS+ then APFS then deleting it ("-") and might be now unformatted space.

So a total clean/erase would help me out? [But it works from the clone so why bother?)

Then I can, using Carbon Copy Cloner, set the system back
But alas the Fusion drive with the HDD under APFS will be no faster anyway, the nightmare that set e off on this track.

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Answer 5

alberti-nl Author

Level 1

36 points

Dec 11, 2020 7:30 AM in response to Loner T

Super, LonerT,

This worked great, altough I got usual errors

[warning: overallocation detected on Main device: (0x21081+3) bitmap address (0x32fc9)

Too many warnings of this type generated; suppressing subsequent ones

The volume /dev/disk1s2 appears to be OK]

All lines of the Disk Utility now show 1,03 TB (would expect a little more as the SSD should be added too,

now I will restart under the internal HD

Diskutil after re-allocation

but I will

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Answer 6

alberti-nl Author

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36 points

Dec 11, 2020 8:18 AM in response to Loner T

This now shows up: [there is only one EFI in the finder; I did the sudo diskutil mount disk0s1 also with disk1s1 after the latter I got:

So now just delete the microsoft part?

Redoning sudo diskutil mount disk0s1 I keep the same finder info; seems logically the same.

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Answer 7

alberti-nl Author

Level 1

36 points

Dec 11, 2020 10:58 AM in response to alberti-nl

I deleted it.

Also tried to get the EFI from the SSD part, but got the message:

Volume on disk0s2 failed to mount because it appears to be

an APFS Physical Store (or is the APFS Container already mounted?)

Note that for this mount operation, Disk Arbitration reports that

the operation is not supported (kDAReturnUnsupported)

See "diskutil apfs list"

So I guess that I see a virtual store (SSD) and a real store (HDD) and deleted the right part.

Will now retsart and then enter command-R

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Answer 8

Loner T

Level 9

59,536 points

Dec 12, 2020 5:03 AM in response to alberti-nl

Glad to be able to assist. Your handle makes me think you are located in Netherlands.

alberti-nl wrote:

You might know, when even a slight anxiety hits, a lot of things get confused - even tough I do have a techical (telecom) degree . .

My work for an ISP also leads to similar anxious moments sometimes. Please post back if you run into any further issues.

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Answer 9

alberti-nl Author

Level 1

36 points

Dec 11, 2020 2:17 AM in response to Loner T

Thanks, this is the output.

- NOTE: Running from external clone on NVME / Thunderbolt

= Internal Macintosh HD/Fusion =

DiskUtil List:

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Answer 10

alberti-nl Author

Level 1

36 points

Dec 11, 2020 2:44 AM in response to alberti-nl

Hi LonerT, Did it from the Fusion drive after restart. No Microsoft there at all !? No BOOT either.

What could this mean?

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Answer 11

alberti-nl Author

Level 1

36 points

Dec 12, 2020 12:32 AM in response to alberti-nl

Thanks LonerT, this has been a most welcome experience.

You might know, when even a slight anxiety hits, a lot of things get confused - even tough I do have a techical (telecom) degree . .

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Answer 12

Loner T

Level 9

59,536 points

Dec 10, 2020 3:40 PM in response to alberti-nl

This can be done without a degree in macOS and Terminal gymnastics. 😉 However, to mount the EFI partition, you will need to run a Terminal command.

sudo diskutil mount disk0s1

This should mount the EFI partition that you can see in macOS Finder. The EFI partition will look similar to

We need to delete the Microsoft directory and empty trash and reboot. Then we can cleanup any partition issues.

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Answer 13

alberti-nl Author

Level 1

36 points

Dec 11, 2020 2:30 AM in response to Loner T

OK, Thanks, I will reboot on the internal HDD and do it.

I expect the command when I run it on the NVMe is not valid when run from NVme. It then says 'Volume EFI on disk0s1 mounted'. But I can't find it :-(

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Answer 14

Loner T

Level 9

59,536 points

Dec 11, 2020 6:00 AM in response to alberti-nl

You have two different issues.

Your iMac has a Fusion drive, which has 1+Tb Fusion, but the APFS Container is 906GB. You are missing 90+Gb.
Your 1TB NVMe has two Fusion containers. Since it is disk0, the EFI partition will not have any Microsoft entries. The Microsoft entries should be one of disk1 and disk2, not disk0. Be aware that a reboot can change the order of disks.

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Answer 15

Loner T

Level 9

59,536 points

Dec 11, 2020 6:59 AM in response to alberti-nl

To get your disk space back, assuming disk3 is the APFS Container at 906GB, you can run

diskutil apfs resizeContainer disk3 0g

which will grow the container to occupy all available disk space. You can then boot from the internal disk, disconnect the external NVMe and we can correct the EFI partition and remove the lingering Windows part.

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How can I delete a non-existant Windows-partition I saw after restart-up /option key?

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