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Duplicates on Catalina MacHD & MacHD-Data volumes

My MacBook Pro is chronically short space and has duplicates of my data on both volumes/containers(?). The files appear to be being updated on the MacHD but I thought they should be on the MacDisc-Data. Neither of the volumes contents identified as aliases implying they are genuine duplicates.


Why is the -Data folder entitled "UserBU" implying it's a backup. Bit odd to have a backup stored on the same drive even if it's in a separate container. What were Cupertino thinking?


To complicate the issue the various duplicated folders (Music, Pictures, Documents etc) are not identical but I'm unsure if it is safe to consolidate all User files onto -Data and delete to copies on MacHD. Am I even allowed to do that? According to Our Glorious Leaders up at Fort Fumble the System volume is supposed to be Read-Only.


Thanks

MacBook Pro 13″, OS X 10.11

Posted on Jun 14, 2021 2:17 PM

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Posted on Jun 14, 2021 4:27 PM

You should have an OS volume and one Data volume. If you have more than one Data volume, it is leftover from a reinstall.

Look in Disk Utility for your Volumes.

The orphan Data Volume will have a mount Point at /Volumes.

The current one will be mounted to /System/Volumes/Data


Files inside of the Container are not duplicates, even if they look like it, unless you have more than one Data volume

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Question marked as Top-ranking reply

Jun 14, 2021 4:27 PM in response to kiwiiano

You should have an OS volume and one Data volume. If you have more than one Data volume, it is leftover from a reinstall.

Look in Disk Utility for your Volumes.

The orphan Data Volume will have a mount Point at /Volumes.

The current one will be mounted to /System/Volumes/Data


Files inside of the Container are not duplicates, even if they look like it, unless you have more than one Data volume

Jun 17, 2021 11:24 AM in response to kiwiiano

ALL of your data is stored in the "Macintosh HD - Data" volume, but the Finder hides this details from users, so you only see one volume.

There is no duplication, because the "Macintosh HD" only contains system files.


Open Disk Utility. If you see something like this:



then everything is ok.

If you see TWO "Data" volumes, then as Barney said you can and should delete one of them, as instructed.

Jun 17, 2021 3:51 PM in response to kiwiiano

The files inside which container? The MacHD or the MacDisc- Data?

Neither are a Container. Those are two Volumes that reside inside the same Container.

There are numerous files and folders in the two User folders that are identical. They are the same size and both open as a separate but identical documents,

Do you see a drive named - Data in the Finder? If so, you did not reinstall correctly and you have an orphan Data drive from the previous installation. You can remove that orphan in Disk Utility as I noted above.

Jun 17, 2021 4:02 PM in response to kiwiiano

When a Mac's drive if formatted in APFS, what we used to call "partitions" are now called "containers." In turn, containers can contain volumes. With the very latest versions of macOS, the OS itself is resident in a read-only "Macintosh HD" volume. All of your apps & user files are in a separate volume, called: "Macintosh HD - Data". These two volumes are considered as a volume group. As mentioned, there should only be one volume group with two volumes inside a single container for macOS. Also, as mentioned, the Finder app (in an attempt to prevent confusion) "labels" the data volume just "Macintosh HD."


So, if you are using the Disk Utility, if you see multiple "- Data" or other named volumes, these are not a part of the macOS volume group, but got there by "accident" from something like a failed OS install or update.

Jun 17, 2021 5:47 PM in response to Tesserax

Thanks, team, I have really been confused! That partition/container things sounds like a “if it ain’t broke, fix it until it is!” situation. I’m now assuming it’s safe to transfer anything in the MacDisc-Data ‘icon’ that isn’t in the MacHD into the appropriate folder of MacHD, then delete the MacDisc-Data with Disk Utility. I didn’t think I had done any OS updates to create a Data thingi but remembered that when I bought the (2nd hand) MBP it had arrived with Catalina about the time Big Sur was released, so I updated because I could. Then discovered that Big Sur stuffed SuperDuper and CarbonCopyCloner. I have chronic problems with the only alternative Time Machine and was reluctant to be bereft of any Backups, so opted to downgrade back to Catalina, which must have created the Data doofer.

Jun 17, 2021 6:17 PM in response to kiwiiano

Not sure if you are using "MacHD" as a short-hand for "Macintosh HD" (which is the default name) ... but if it actually is "MacHD," it would have been renamed somehow. We also don't know how you got to this situation in the first place. The fact that you stated you also had a volume named UserBU indicates some type of user interaction as well. We could try to "piecemeal" your Mac's drive back together again, but at this point, I think you will be better served by first completely erasing the drive, and then, install a fresh copy of macOS ... at least, that's what I would do.

Jun 19, 2021 3:10 AM in response to Tesserax

Problem cleared Team. I'm slowly getting my head around Catalina's quaint ways, having spent years back at Yosemite, and your suggestions have been invaluable. Many Thanks.

I decided to have a go at deleting one or other of the -Data offerings in DiscUtil, first backing up anything that could be from the Desktop icon.

According to DiscUtil one -Data had a greyed out minus and the other didn't. But when I bit the bullet and tried deletion, it balked out claiming it was in use for some obscure process. I rebooted everything in sight and had another go....Success!! I now have only the MacHD icon on the Desktop.

I compared the contents of the User Folder on both the MacHD and -Data backup and found that while there were more items in some MacHD folders, the file sizes were the same if there were duplications. I do have a Super Duper clone out in the office so I'm reasonably confident I haven't trashed anything crucial. If I have, tuff titty, I'm retired now and there are plenty of worse things that can happen.

Thanks again, everyone.

Duplicates on Catalina MacHD & MacHD-Data volumes

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