I have a Samsung T7 SSD connected to my Thunderbolt 3 USB Type-C port. I noticed a couple of things that seem odd, and I wonder if that is because it is external:

  • Disk Utility will not let me convert/erase it to APFS, even though I'm running Big Sur.
  • I keep getting asked "X would like to access your external drive" for every single application.
  • It has a "Eject" button in Finder.

On my old Mac, I had an external boot drive connected via USB and none of these were the case. There was no obvious way to see it was not an internal drive. Is there a way I can get my Mac to treat this new external drive like an internal drive? I do not want to keep granting permissions and I do not want to accidentally eject it!

As requested, here is some data:

% diskutil list external
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                 Apple_APFS Container disk3         1000.0 GB  disk2s2

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1000.0 GB  disk3  
                                 Physical Store disk2s2
   1:                APFS Volume Data                    261.7 GB   disk3s1

Does not mean much to me. Why do I have a 209.7 MB disk?

  • 1
    1. How are you trying to convert/erase it, at volume or device level? 2. [no idea, probably you haven't set perms properly, we would need more detail] 3. Why would you want to do that for a drive which may need to be unplugged?
    – Tetsujin
    Jul 28, 2021 at 18:46
  • It's my primary data drive, it just happens to be external. I opened Disk Utility, selected the drive, selected Erase. Whatever the defaults are :)
    – Mr. Boy
    Jul 28, 2021 at 20:10
  • Disk Utility gives same results for device or volume... exact options differ slightly but APFS isn't listed.
    – Mr. Boy
    Jul 28, 2021 at 20:16
  • 1
    If APFS is not listed, then you probably have not selected "GUID Partition Map" as the Scheme. Jul 29, 2021 at 3:21
  • @Mr.Boy Can you add at your question, T7 plugged, the results of terminal command : diskutil list external?
    – user415185
    Jul 29, 2021 at 6:09

1 Answer 1


The T7 SSD has been converted/erased to APFS. The macOS operating system automatically creates a small EFI partition at the beginning of drives with a GPT and size above a certain limit. I suppose this is done incase you choose to install a operating system now or in the future. You can not accidentally eject an external drive that is in use by an application. You can select "Full Disk Access" under the Privacy tab of the Security & Privacy pane in the System Preferences application to add applications. This may reduce the prompt for access.

  • Good point that you cannot eject while in use. I'm still curious though; on my old Mac I boot from an external drive and it is not reported as external. I assume due to cloning my internal drive-volume, or just MacOS explicitly shows boot/startup drive as non-ejectable because it would make no sense.
    – Mr. Boy
    Jul 30, 2021 at 16:25
  • I might be able to simulate your old Mac in VirtualBox. What model/year is the old Mac. What version of OS X/macOS was installed. Are you booting from the T7 on the current Mac? Ejectable is not the same as External. My Samsung X5 Thunderbolt 3 drive reports as external, but is non-ejectable regardless of whether the 2018 Mac mini boots macOS Mojave from this drive. There are different methods to clone a drive. What method did you use? Jul 30, 2021 at 19:49
  • 1
    If you boot from the external drive - it won't matter any more if any app "uses it" or not - it's being used all the time by ALL MacOS system processes launched from it, so you won't be able to eject/dismount it, unless you physically detach it. Aug 3, 2021 at 18:33

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