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ignatius345

macrumors G3
Original poster
A few times a week, on average, my external SSD unmounts itself overnight and then subsequently remounts. I wake up to the drive connected, but also a warning alert from macOS about ejecting drives before unplugging them.

The setup:

- iMac M4 with 4 Thunderbolt ports, running Tahoe
- Crucial X9 portable SSD, about 17 months old
- Anker Thunderbolt 4 cable (this one)

I’ve tried using a different cable, and that doesn’t seem to help. In fact, the issue started with a generic USB-C data cable and I switched to the Anker Thunderbolt cable, but it’s still ejecting/remounting overnight. I don’t quite remember when the issue started, but it’s been some months. I can’t say for certain whether it started with Tahoe or not.

Anything I should check, or anywhere I should look in logs or whatever to see what’s making it eject?
 
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Do you have "put hard disks to sleep when possible" enabled?
I did! Just switched it off. I can’t believe I didn’t spot that. Thanks, maybe that will fix it. 🤞

Is the external drive connecting as a USB drive or Thunderbolt?
USB 3.2 Gen 2, at 10 Gbps

Just pulled this from WhatCable (awesome app).
iMac 2026-08-20 at 12.56.48 PM.png
 
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