User profile for user: Andrew Shalit
Andrew Shalit Author
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118 points

External hard disks not visible to new MB Air running MacOS Ventura

I have a new 15 inch MacBook Air running MacOS Ventura. I have been able to attach a couple of external SSDs, but I have two external hard disks that I cannot access from the MacBook. When I plug them in, they don't mount. Moreover, they are not visible from Disk Utility. It's like nothing is attached to my computer at all.


Do I have to do something special to allow my Apple Silicon MacBook Air running MacOS Ventura mount external disks?

MacBook Air 15″

Posted on Aug 18, 2023 3:37 PM

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User profile for user: Andrew Shalit
Andrew Shalit Author
User level: Level 1
118 points

Posted on Aug 19, 2023 8:04 AM

I found the problem. There appears to be a bug in MacOS's handling of new USB devices when multiple users are logged in (via fast user switching).


The first time you attach a new USB device to your computer, MacOS asks you to give permission to connect to the device. This is a security measure. The device will not connect without your permission. The following movie shows what is supposed to happen.




That works fine when only one user is logged in. However, when there are two users logged into the computer, the dialog flashes briefly on the screen and then disappears. There is no way to give permission, and it's almost impossible to see what the dialog says.



The good news is that this only happens the first time you attach the device. Once you grant permission, the computer will successfully attach to the device even if multiple users are logged in. So it's easy to work around the bug, once you know what's happening.


I'll report this to Apple when I have a few minutes to spare. Thanks to all who gave suggestions for figuring this out.

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User profile for user: Andrew Shalit
Andrew Shalit Author
User level: Level 1
118 points

Aug 19, 2023 8:04 AM in response to Andrew Shalit

I found the problem. There appears to be a bug in MacOS's handling of new USB devices when multiple users are logged in (via fast user switching).


The first time you attach a new USB device to your computer, MacOS asks you to give permission to connect to the device. This is a security measure. The device will not connect without your permission. The following movie shows what is supposed to happen.




That works fine when only one user is logged in. However, when there are two users logged into the computer, the dialog flashes briefly on the screen and then disappears. There is no way to give permission, and it's almost impossible to see what the dialog says.



The good news is that this only happens the first time you attach the device. Once you grant permission, the computer will successfully attach to the device even if multiple users are logged in. So it's easy to work around the bug, once you know what's happening.


I'll report this to Apple when I have a few minutes to spare. Thanks to all who gave suggestions for figuring this out.

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User profile for user: Andrew Shalit
Andrew Shalit Author
User level: Level 1
118 points

Aug 18, 2023 3:42 PM in response to Andrew Shalit

Update: when I run a system report, the external device shows up. But for some reason the Finder and Disk Utility don't see it.


EXTERNAL_USB:

  Product ID:	0x0906
  Vendor ID:	0x0480  (Toshiba America Info. Systems, Inc.)
  Version:	0.00
  Serial Number:	20230709001710F
  Manufacturer:	TOSHIBA
  Location ID:	0x00200000
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User profile for user: MacMikeInOK
MacMikeInOK
User level: Level 4
3,704 points

Aug 18, 2023 4:29 PM in response to Andrew Shalit

I'm a bit surprised they aren't visible in Disk Utility, as I would have guessed they need to be erased/reformatted.


Any chance you still have your old Mac? Have you tried plugging them into that?


What are you using to adapt the drives to the Thunderbolt ports on your MacBook Air? Did your old Mac have USB-A-type ports that you didn't need an adapter for?



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User profile for user: Barney-15E
Barney-15E
User level: Level 10
119,052 points

Aug 19, 2023 4:25 AM in response to Andrew Shalit

Are they bus-powered drives (no external power supply)?

Those can try to pull more current than available on the bus, disabling it, and the drive won’t mount. As portable HDDs get older, they tend to do that.

If it is a spinning HDD, you will usually hear or feel it spin up, then spin down, repeating that cycle.

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External hard disks not visible to new MB Air running MacOS Ventura

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