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macOS I/O is stuck when plugging USB hard drive, although one partition mounts successfully

Hello folks,


I'm curious to read any take on the following behavior from macOS which I can't explain.


I used an external USB drive (WD Elements 1TB) successfully for various months on my MBA M1 2020, hosting 2 partitions on it:


1) a DATA partition (FAT) of some 50 GB

2) a Time Machine partition (APFS encrypted) for Time Machine


As the disk is connected to my USB-C display, it happened several times that I unplugged my computer without un-mounting the drive.


What's happening now is the following:


  1. I plug-in the USB drive
  2. the DATA partition is mounted. It doesn't show in finder, but I can successfully `cd /Volumes/DATA` and read files from it.
  3. I/O on the rest of the system gets stuck. I can use open applications, e.g. open new Tabs and loads websites in safari. But I can neither start applications (they just keep bouncing endlessly in the Dock), now launch binaries from the Terminal.


What's also interesting:


  • There's no trace of a problem of any sort neither in /var/log/system.log nor in any group of Console.app
  • The Disk Utility application does not list the physical drive, despite the DATA partition from it having been mounted.
  • The Disk Utility application actually becomes unresponsive after a few seconds – plain operations like selecting Drive entries from my MacBook internal drives also don't work.
  • Running `diskutil list` from the terminal also gets stuck.
  • As soon as the USB drive is unplugged from the Mac, macOS becomes immediately operational normally. Apps that kept bouncing in the Dock without opening minutes long immediately open.
  • Plugging the drive into a Windows computer is no problem. The DATA partition shows up normally and the rest of the system keeps operating normally.


Any hint?


cheers

michele

Posted on Jan 16, 2022 4:47 AM

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Question marked as Top-ranking reply

Posted on Jan 16, 2022 6:42 AM

YOu said "As the disk is connected to my USB-C display, it happened several times that I unplugged my computer without un-mounting the drive.".


What happens when you connect the drive directly to the Mac?

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macOS I/O is stuck when plugging USB hard drive, although one partition mounts successfully

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