Just got a new M1 Mac mini a couple weeks ago and upgraded from a 2013 iMac. So far it’s been great, but I’ve noticed one weird thing. When I login, I am occasionally seeing that my Time Machine hard drive is unmounted. I never saw this occur with the iMac once. I’m not sure if it has to do with the machine itself or if this is something going on with Big Sur, as the iMac wasn’t upgradeable to it. I have the drive attached to one of the USB C / Thunderbolt ports on the back. There doesn’t seem to be any discernible pattern to it either. Just seems to happen once or twice a week randomly. Anyone else see this occur and figure out what’s going on? I thought about giving one of the USB A ports a try and I might do that today, however, I was using all of those for other things. Might be time for a hub for this thing if that stops it.
I have a Mini M1 with the most recent version of big sur. I use a spinning HD via USB A for Time Machine. It works fine. I have other SSDs connected via USB C. They also work fine. I wonder if there’s a problem with your USB C/Thunderbolt cable.
It could definitely be the cable. I just bought this one off of Amazon a week or two ago. It’s by a company called Cable Matters, which I’ve had good luck with in the past for display cables, but who knows. Going to try a different cable to see if it helps. Just out of curiosity @neonate what brand cables are you using?
I too moved from an iMac (2017) that had no issues to an M1 Mac mini when the latter was first released, and have had the same issue you are describing. Both with my Seagate Time machine drive and an OWC thunderbolt drive i use for a Carbon Copy Cloner backup I run about once a week. The Seagate is USB-A and plugged in continuously. The frequency of unexplained dismount has steadily decreased and the Seagate cable indeed seems to be more “loose fitting” with the Mac Mini for some reason than the iMac, so any wiggle of the cable I think is why it dismounts. The OWC Thunderbolt drive (purchased 2018) is a bit more annoying as sometimes it works flawlessly and other times it dismounts before completing the task.
I use the cables that came with the drives. The Spinning HD is a G-Drive from G Technology (USB-A). The SSDs are SanDisk (USB-C). The G-drive has it’s own power brick. The SSDs are bus-powered (I think that’s the term).
Was recently having similar problems and it turned out to be a cable. I would just brush my hand over it and it would disconnect. Will be very glad when USB 3.0 Micro Type B is out of my life.