Help me undo something SPECTACULARLY stupid >> partitioned main drive!

Goodness. I have done something so incredibly asinine, that I was actually hesitant to write this…
Mea culpa, mea culpa.

Please help. Seriously worried I might make things worse, if not careful.

My external HDD – connected via a USB-hub into my 14" MBP – as a TM volume, started giving me issues and couldn’t be repaired via Disk Utility.
It was struggling to load, took forever to recognise my encryption password, and started making noises.

Bought a new external, WD Elements. Same connector cable as the last one (Seagate).
So I simply disconnected the Seagate, plugged the WD Elements in.
Opened Disk Utility. Looked for the new drive to format – since I always format new HDD’s.

See [Data] listed as a drive on the left, which must be my new drive.
Note that it is unusual that I cannot select “erase” or “first aid”, but see “partition” is available.
Simply assume that this is how the new Disk Utility functions in Monterey 12.4…
Did I mention I was in a hurry, and wanted this to erase/set-up new volume in the background, while I popped out for a quick meeting?

Asked me if I wanted to make it APFS – said yes, went with encrypted option, and typed in my usual password.
It does its thing. Wow. That was quick.

See that I only have 83GBs available, and that 411GBs is taken up by “other volumes”.
Stare at the screen.
Unmount it. Remount it, fill in password.
Same result.
Open Time Machine, and try to add the new WD Elements – no option to add new disk.
Stare at the screen.

Glance at WD Elements to check that I had in fact connected it to my hub. Check.
Glance to see if USB-c to hub cable is seated properly.
Notice it is not plugged in. Uh-oh.

Plug it in.
Stare at the screen.
Realise I have just partitioned, with encryption, my main DATA drive/SSD, of my laptop.
WD Elements is now sitting in Finder, waiting for me to format it!


What. Do. I. Do. Now?
I realise(?) the APFS partition is dynamic, and so – shouldn’t take space away from my main drive storage – correct?
But, suffice it to say, this was not the plan…

Do I:
(a.) “Erase” the newly-created partition? Or do I…
(b.) “Delete the APFS volume”??

All the websites I have checked, speaked of permanently deleting any data stored on it.
Am I correct in that, as it sits there now, it has no data – and taking it away, should result in any loss of data elsewhere?
So think deleting the volume should be the one??

Any advice would be sincerely appreciated!


First of all, I would consider to copy the remaining Data from the Drive to a safe place!
Then I would try to erase the new partition, and increase the old partition again with the space available now.
If this is not working, I would erase the drive, and set it up again!
Thereafter I would copy the previously copied Data back.


Thanks for the suggestions – I have resolved things, but not before 1st making a new backup, as you recommended.

This Apple Support article was enough of a guide for me, to make the call:
From what I gather [ and please, future reader, do NOT assume me to be correct in this ], APFS has several new features, one of which is to allow multiple volumes to be easily made, that dynamically extract “storage space” from all over the main drive.
[Partitions (don’t quote me on this), are more “fixed” containers that delineate specific space – though, to be fair, volumes can do that as well…]

But regardless, the above was enough to have me realise I had created a dynamically adjustable volume on the main drive (albeit encrypted), that presently had nothing in it.
And the warnings pertaining to data-loss, applies to any data being stored there – not data underlying that volume, and somehow part of the main disk.
Erasing the volume, would merely leave it in place (as created), but with all content wiped [for one to start over, in essence].
Deleting the volume, removes it in totality, as if it was never created in the first place.

Since I was staring at a “volume” created on my main drive, with nothing in it – I used Disk Utility to “delete the APFS volume”.

Pleased to report that several nerve-wracking seconds later, all was back as it was before.
Goodness >> nothing major after the fact, but certainly a more hairy situation a few hours ago.

Moral of this silly tale of woe: Double check which drives are being selected, before doing anything in Disk Utility. And don’t use Disk Utility when you are distracted/rushing to a new appointment!


Whew! I expected that you should be able to easily reverse this (given Apple’s new disk architecture), but it must have been nerve-wracking to delete that volume!

I think the design of Disk Utility is partially at fault. The labels “Internal” and “External” are small and very low contrast (grey on grey, Apple’s favorite awful design language). Not to mention the default setting which doesn’t show devices, only volumes.


Thanks! Very relieved! :smiley:

Reckon the design played a role for sure.
Admittedly, this was combined with the “old” drive taking forever to authenticate the password yesterday – there was a stage yesterday when the password-entry window was open, AND the drive was still listed under Finder (as mounted/connected), when it had been yanked.
That had me thinking it was connected, despite my not interacting with it much today.
And, still, I shouldn’t have rushed.

But regardless, over on the sidebar in Disk Utility, I see:
“Macintosh HD volumes” at the very top, then indented under it comes “Macintosh HD” (the encrypted HD), then indented under it comes “Macintosh HD snapshot”, and then only “Data” – it was pushed far enough down the side-bar menu that the quick glance fooled me, with my not noticing the [Internal] and [External] distinction, as you mention.

I have listened with some interest the comments pertaining to bad design in the latest versions of macOS over on ATP… Again, not saying I was blameless – but making things more explicit visually could very possibly have prevented this silly mistake…

Kudos and congrats to you! This was a tricky one! You are truly a Power User!


I added a like to OP’s post. Let everyone who’s ever done something like this or worse (like me) also add a like so OP doesn’t feel quite so bad!