External TimeMachine disk disconnects randomly

I have MacBook Pro (14-inch, 2021) 16 GB and am running Monterey 12.2

I have an external LaCie 4TB rugged hdd as Time Machine backup, which works nicely most of the time.

But from time to time, the hdd disconnects randomly, and I get the messge that I should unmount before disconnecting. The hdd is not in the Disk Utility anymore, and when I disconnect the USB 3 cable, connect it again, it works (after some waiting, peesumibly checking the fs). Happens on all three USB C ports and using different cables, one an Apple thunderbolt cable.

Any suggestions? I aam not to keen on wiping my time machine backups anr re-format as APFS…

Perhaps use the Disk Utility to do “First Aid” on the drive?

I did - several hours later everything OK.

I’m having random disconnects too.
I think it’s a Monterey thing.

  • The occasional message of eject before disconnecting.
  • A random error when my backup tries to run saying my external raid-paired SSDs aren’t mounted.

I don’t have to intervene in either case, things work correctly afterwards.

Didn’t happen on Big Sur.

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OK - I’ll observe it (but after connected to a CalDigit hub, no dosconnects so far for 6 hours), but I am quite sure I had to physically unplug the drive and plug it back in to get it back.

But I’ll see.

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FWIW, all my drives are connected directly to my iMac Pro.

I have seen this on an older Mac Mini on Mojave 10.14.6 - happens every few months - and it looks like the drive is connected when I later see the message. Odd…

Looks like reports like these started back in late October.


I’ve had this issue with Time Machine drives directly connected to multiple iMacs, and connected through a hub to a MBP, all running up to Catalina and earlier (I haven’t upgraded my machines beyond that yet, yikes). I have a recurring OF task to “check iMac Time Machine” every 2 weeks. My MBP gets unplugged and replugged in enough that I don’t need to go out of my way to check it, but not infrequently the Time Machine drive will simply not mount and not even show up under Disk Utility.

#shrug #itjustusuallyworks

So it seems, there is nothing one can do at the moment - just wait until #itjustworks

Quick follow up: which drives are the ones disconnecting? We have two drives 2.5" (two WD, one LaCie) and only the LaCie is disconecting - OK - the WD was connected to the hub via USB A connector, the LaCie via USB C.

I have two of these Thunderbolt 3 drives setup as RAID 0

And a WD Red WD40EFRX in a generic enclosure.