Can I Unify "Two" Drives?

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Level 1

41 points

Can I Unify "Two" Drives?

Hi all! I'm a brand new Catalina user, just being forced to upgrade from High Sierra after buying a new iMac.

Something went wonky when moving files from my old machine to the new through Migration Assistant, and I was left with a machine that wouldn't let me log in. I figured the best thing to do would be to nuke the new system and reinstall Catalina from scratch, then manually reinstall my various apps.

After formatting the internal drive, I ended up with two volumes on my desktop: Macintosh HD and Macintosh HD - Data. (I'll refer to them from here on out as "System" and "Data".) I did some reading and now understand the reasoning behind this and recognize they're both on the same physical volume and sharing the same space. But I also see where it should show up as a single drive on the desktop, yet in my install, they still appear as two separate volumes.

My assumption was that I should work from the Data drive and leave the System drive alone. Trouble is, because the Desktop Folder lives on the System drive, if I have a file on the desktop that I want to move to a folder on the Data drive, it's not just a move--it's a copy, followed by having to manually delete the one on the desktop. A bit of a PITA.

So...is there any way, post install, of reunifying those two drives aside from formatting and starting from scratch again? Can DU retroactively place the two volumes into a container that will show as a single volume without nuking everything? Should I just move everything to /Users/me/ and live there and ignore the Data drive? Am I better off just biting the bullet and doing another format and reinstall? Any suggestions would be most appreciated!

Specs, if it helps: Retina 5K 27" 2020 iMac, 3.6GHz 10-core i9, 4TB SSD, 128GB RAM, Radeon Pro 5700XT running 10.15.6 (19G2021)

Thanks in advance for any help!

iMac Line (2012 and Later)

Posted on Aug 29, 2020 7:09 AM

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Answer 1

Top-ranking reply

Luis Sequeira1

Level 9

67,276 points

Aug 29, 2020 8:14 AM in response to Ben Scripps

You probably can get back to normal by removing the smaller of the two "Data" volumes.

IMPORTANT: Make sure you have backups. The procedure I am about to suggest will delete stuff, hopefully nothing you need, but be warned.

First, in the Finder, to make sure, select the "Data" volume in the sidebar and press Command-I. Does it use some 300GB?

Do the same for Macintosh HD. Does it use some 1.9TB (roughly the 11GB + 1.89TB from the above screenshots)?

Then all you should need to do is:

Open Disk Utility.

Select the 300GB "Data" volume. Control-click and choose Delete APFS Volume...

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Answer 2

Aug 29, 2020 7:35 AM in response to Ben Scripps

Your problem is that you failed to erase the whole drive and only erased one volume.

Make sure you have a backup.

Open Disk Utility. What do you see? One Macintosh HD and two Macintosh HD - Data, or vice versa?

How much space does each of them take?

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Answer 3

Ben Scripps Author

Level 1

41 points

Aug 29, 2020 7:47 AM in response to etresoft

Last login: Sat Aug 29 10:44:22 on console
myUserName@myMachineName ~ % diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         4.0 TB     disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +4.0 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD - Data     304.8 GB   disk1s1
   2:                APFS Volume Macintosh HD - Data     1.9 TB     disk1s2
   3:                APFS Volume Preboot                 82.9 MB    disk1s3
   4:                APFS Volume Recovery                528.9 MB   disk1s4
   5:                APFS Volume VM                      2.1 GB     disk1s5
   6:                APFS Volume Macintosh HD            11.1 GB    disk1s6

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Answer 4

Aug 29, 2020 8:15 AM in response to Luis Sequeira1

For future reference: when you "nuked" the system, what you should have done was: select View->Show All Devices; select the whole drive (not just the Macintosh HD volume) and erase (choosing GUID partition table and APFS).

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Answer 5

Ben Scripps Author

Level 1

41 points

Aug 29, 2020 8:36 AM in response to Luis Sequeira1

This is starting to make sense to me now...

Looking at the screenshots I posted, DU shows three drives; one is Macintosh HD and has the Finder icon on it, and is where the OS lives. The second is the first "Data" drive which is blessed with the Home folder and shows the Home folder icon in DU. The third is the second "Data" drive without any extra icons and is the one that's showing up on my desktop as a separate drive. In other words, the "Macintosh HD" icon on the desktop is actually the first two as a single logical unit, and the "Macintosh HD - Data" on the desktop is that third one and is where I parked all my restoration data originally.

So if I'm reading you correctly, I should be able to just move everything from that "Data" drive into my Home folder, then once it's there, delete the third one in DU and I should end up with just a single drive on the desktop.

And I'll be careful; I know the value of a good backup. :-) My old iMac is sitting next to me with everything still intact, and my off-site is always available if I need it.

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Answer 6

Ben Scripps Author

Level 1

41 points

Aug 29, 2020 10:40 AM in response to Luis Sequeira1

Went exactly as planned--I got everything moved off the "Data" drive into the "Macintosh HD" drive's Home folder and deleted the APFS Volume through Disk Utility and after a restart to be sure, I'm back to a single unified drive on the desktop. Thanks so much for your help!

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