Macintosh HD and Macintosh HD Data?

Agreed- I upgraded to Catalina and most of my apps wouldn’t work so I reverted the update by restoring to an earlier version and then copying my files over. I now am unable to delete any of my files because my disk is full. I have a feeling that it duplicated my drive because I also have “Macintosh HD- Data” which what looks to be a second drive.

Yes please, it seems as though my hard drive is partitioned in some way. I usually am on point with this stuff, but ive never seen it say Mac HD Data before and I think its actually doubling my information.

Hey everyone! I finally got the answer I have been looking for for weeks! I can finally resume my normal work. Basically what happened is that once you upgrade to catalina, it partitions your hard drive to be a “ghost copy” meaning that it says Mac HD and Mac HD Data. When you go to downgrade from Catalina (for my case because most apps wouldn’t work) it’s basically keeping it as a partition instead of deleting that ghost image. For me I was unable to delete anything, even unmounting that partition. The way you are able to fix this is by going into recovery mode, unmounting the hard drive partition, and then erasing it. Problem solved, I now have more than 130gb free!

Thank you. I can do that BUT when I reinstall from a TimeMachine backup, like from the day before, won't it reproduce that ghost data. Will not the TimeMachine backup have both the Mohave data etc. I want and the Catalina I abandoned? Or it doesn't work that way?

When I decided to abandon Catalina and go back to Mohave, I did NOT first install Mohave and then setup as a new computer. I did the entire reinstall from a TimeMachine backup. Is this where I f**ked up?

The Time Machine backup just backs up the file tree, not the operating system itself. When you downgrade you need to wipe the system disk, reformat it and install Mac OS. You can then restore your data from Time Machine. But Time Machine does not reformat the drive.

No need to reinstall from a TimeMachine backup, but if you do that is ok. What you NEED to do is go into "Recovery Mode" when restarting your Mac. It will bring up an option for "Disk Utility" and that is where you un-mount and erase "Macintosh HD Data."

Helpful for only people that are running Catalina. Many people are looking to downgrade their system and the ghost hard drive is getting stuck in translation. Like I have been mentioning if anyone is having any of these problems, they should boot into recovery mode, unmount that hard drive and erase it.

Guy... I'm referring to people that are downgrading from Catalina to Mojave. If you read my above comments and the issues that I ran into, you would understand that Mac HD Data does not need to be there.. ONLY if you have CATALINA should it stay there, NOT Mojave...

Yes, that is true, but if you just delete Mac HD Data and don’t reformat the drive all of the space it occupied becomes unusable. For some strange reason I am not willing to give up half of my storage.

Yes, that is true, but if you just delete Mac HD Data and don’t reformat the drive all of the space it occupied becomes unusable.

The Data volume is a Volume in an APFS Container which means it doesn't have any dedicated storage of its own. Deleting the volume will return every bit of storage it used because the storage is shared amongst all volumes in the same container.

It is not a disk or a partition or anything similar.

This really makes no sense to me. Why would you show a HD and an HD - DATA?

A reason is stated but the explanation is not clear to the me. Should two drives appear on my desktop or not? If they are sharing the same hard-drive space, but are each showing up with two drive spaces that supposedly share the same space what is the point other than to confuse? Why did they only show up one the reinstall? This is very confusing.

What is going on here?

Oh, and BTW, Siri just popped up when I was writing this three times, even though I expressly asked many times to please go away. Perhaps you could send this to the appropriate people?

Should two drives appear on my desktop or not?

No, it should just show one, but if two appear, it doesn't really matter.

Confirm you are still running Catalina and didn't revert back to Mojave.

Perhaps you could send this to the appropriate people?

I don't know who the appropriate people are, either. But, I couldn't send it to them even if I knew.

Should two drives appear on my desktop or not? If they are sharing the same hard-drive space, but are each showing up with two drive spaces that supposedly share the same space what is the point other than to confuse? Why did they only show up one the reinstall? This is very confusing.

What is going on here?

Catalina changed the filing system; your hard drive is still one drive, but it now has two volumes: Mac HD which is read only and contains the OS and system files (and cannot be changed so it cannot be accessed by malware, etc) and the Mac HD - Data which contains the apps and your files and which is read/write so you can make changes.

As mentioned, only one should show on the desktop.

If you do a reinstall correctly - meaning you first erase the entire drive - then only one drive should show on your desktop. The only place to show two volumes would be Disk utility.

And, FYI, we are all other users here and do not work for Apple, so we cannot send anything "to the appropriate people:". You will need to contact Apple for this.

After finding that the majority of my Apps would not work on Catalina I decided to reinstall Mojave. What a nightmare, it would not go back with TimeMachine, so tried erasing the HD, no matter how many times I erased the HD the DATA folder was still there. I reinstalled Mojave anyway and it is showing the HD and DATA disk with 121GB which is impossible as I only have 140GB,. Just living with it as it is not affecting anything. This is a total screw-up by Apple!

Come on Apple, SORT IT!