Sequoia: USB External Drive Spontaneously Un-mounting

I have an M1 Mac mini and my external USB drive (USB-3), which was rock-solid under Sonoma, now spontaneously (and seemingly randomly) un-mounts.


It will even un-mount if it is in use! This makes, for example, completing a Time Machine backup very unpredictable.


This drive *does* auto-mount (albeit slowly) when the mini is booted, and it will re-mount on its own (slowly) after un-mounting, but at that point the damage is done.


I have disabled "Put hard disks to sleep when possible" in System Settings>Energy.


I am on macOS Sequoia 15.2. But this happened on earlier versions of Sequoia, too.


I don't see what could be wrong since this drive worked *perfectly* when I was running Sonoma.


Any tips?




Mac mini, macOS 15.2

Posted on Jan 9, 2025 8:40 AM

Reply
1 reply

Jan 12, 2025 7:30 AM in response to MJ

MJ wrote:

I have an M1 Mac mini and my external USB drive (USB-3), which was rock-solid under Sonoma, now spontaneously (and seemingly randomly) un-mounts.

It will even un-mount if it is in use! This makes, for example, completing a Time Machine backup very unpredictable.

This drive *does* auto-mount (albeit slowly) when the mini is booted, and it will re-mount on its own (slowly) after un-mounting, but at that point the damage is done.

I have disabled "Put hard disks to sleep when possible" in System Settings>Energy.

I am on macOS Sequoia 15.2. But this happened on earlier versions of Sequoia, too.

I don't see what could be wrong since this drive worked *perfectly* when I was running Sonoma.

Any tips?




I would try a different drive and compare your results...



Erase and reformat a storage device in Disk Utility on Mac


https://support.apple.com/guide/disk-utility/file-system-formats-dsku19ed921c/ma



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Sequoia: USB External Drive Spontaneously Un-mounting

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