I'm trying to back up a Mac for a friend who moved and left her 2020 iMac 27 (Intel) with me. She is having me send her the data from it and then sell the Mac. The 1TB SSD iMac hard drive is in APFS format. I'm backing up to a Seagate (ST2000LX001) FireCuda 2TB Solid State Hybrid Drive in a USB-C external enclosure.

Things I've tried:

  1. Created external drive as APFS and used Time Machine to back everything up. I tried to open it on an older (2017) Mac like her MacBook Air that she took with her. I don't see the drive as there at all. It does not mount.

  2. Started over: Created external drive as Mac Journaled Extended and used time machine. The older Mac sees/mounts the disk but all the user files are locked (see pic & seem to be empty)

    enter image description here

  3. Created external drive as FAT. Then, I used Finder to just copy the user directories in /Users one at a time. Takes hours and invariably fails to complete. Some error happens hours into copying and it terminates the copy process with no hint as to what got copied and what didn't.

I either wind up with a drive that old Mac computers can't read, a drive that they can read but not see anything, or a partial copy.


What I'd really like to do is:

  1. Go into terminal
  2. Sudo to root
  3. Issue some command that copies everything to the external drive ignoring errors and does so without carrying over the macOS authentication scheme.

So I'd just wind up with an external drive full of her and her family's data that they could easily access without having to deal with permissions nonsense.

What is the best way to achieve this?

  • Mac I'm backing up is 2019 Retina 5k 27" running Big Sur
    – fbonds66
    Apr 17, 2022 at 17:35
  • missing screenshot ibb.co/HBfPvNL
    – fbonds66
    Apr 17, 2022 at 17:38
  • 2
    This is an excellent example of an XY problem, you’re asking how to attack only a portion of the larger problem. Who has permission issues and what OS is going to do the reads? I’ll make a general answer, but there’s a lot not clear yet - keep on editing and if possible, use the native image tools for stack exchange. You can’t edit this too many times as we narrow what you need to learn or get for this to work
    – bmike
    Apr 17, 2022 at 17:54
  • I disagree with the XY problem comment. I’m perfectly clear what I want to do and why it makes sense to do it. The problem statement details what is immediately available in the MacOS to extract the data to disk and how that doesn’t accomplish my goal.
    – fbonds66
    Apr 18, 2022 at 13:50
  • 1
    Do you need a backup of the whole drive or just the user content in /Users? Looking at your attempt you just need /Users, so I would format an external SSD drive with APFS and then just use rsync or ditto to copy everything.
    – nohillside
    Aug 3, 2022 at 16:55

3 Answers 3


Let’s see if we can address the issues and help you go forward. I’m going to address this in the order presented.

  1. Time Machine on an “older” Mac. It’s not so much that the Mac is older, it’s the version of macOS that’s not compatible with an APFS container. The Mac needs to be running High Sierra or newer.

  2. Locked Files/Folders. This is a permissions issue. Either you or your friend need to take ownership of the files/folders and then you’ll (she) will be able to access them. Even if you have the exact same username, the UUID (unique identifier) is different so macOS automatically says “Nope! You’re not allowed.”

    I’ve written instructions on how to take ownership of files in a related question.

  3. Finder copying files. Finder should copy the files over, but you will likely run into an issue with ownership (see point 2). As for the file format, HFS+ is likely a safer bet and will be higher performance. You can reformat the drive using the GUI Disk Utility or with the command line utility diskutil

    This command will repartition your drive with a single HFS+ partition, readable by pretty much all Mac computers running OS X/macOS. Remember to use the identifier of your drive. You can obtain it by running the command diskutil list.

    diskutil partitionDisk /dev/diskX 1 GPT HFS+ NAME 100%

Now, you have some options.

  • You can take ownership of the files and copy them over to your newly formatted drive using Finder

  • Using Terminal, you can copy over the files as follows:

    cp -R /Users/* /Volumes/NAME_OF_EXTERNAL_DISK

    Alternatively, you can archive them as a single tar file:

    tar -cvf MyFriendsStuff.tar -C /Users/username/

    To compress the file (zip) it, you can do so by adding the z flag:

    tar -czvf MyFriendsStuff.tar.gz -C /Users/username/

    Once the archive is created, you can copy that to the external drive (yes, you can have the archive created directly, it’s just my personal preference to create then copy).


The easiest way to clone is to have a hardware device just clone the drive.

If you can’t get the drive out, you could boot to recovery and use disk utility or asr to clone the entire drive. That would save you from needing to ship the computer back to where you can work on it directly.

Once you have it or the clone, I think you want export instead of backup. The latter exists to serve the restore process. When you say anyone can read, that implies you need an export that covers android, Linux, windows, Mac, across 10 to 20 years of operating systems.

You won’t go wrong If you set up time machine and let it format the drive on the assumption that to read it you take that drive to any Mac that’s newer to do the read and export if needed to narrow to a non-apple OS. I would not use two macs for this - much simpler to let the Mac with the data manage the backup. Target disk mode and ignore permissions might help, but you’ll back up a ton of data you don’t likely need if you only want documents.

Also, using migration assistant to move the account over also might help you simplify things if you get them both in the same room.


You may overcome the 'locked' status of files if you check the box "Ignore Ownership on this volume" in Get Info.

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