I just upgraded to LM 17 Cinnamon 64-bit from LM 16 Cinnamon 64-bit. Suddenly I have a mechanical USB 3.0 hard drive that mounts, then unmounts, then re-mounts, etc...all on its own. It will not stay mounted. It will stay mounted for a few minutes sometimes then unmounts, then re-mounts, etc. seemingly with random timing.
It's a Seagate Backup Plus 1 TB - based on a 2.5" mechanical disk, the type that is powered by the USB bus and needs no external power. It worked fine in USB 3.0 mode on LM 16. Now it will only stay mounted when connected to a USB 2.0 port.
I was thinking it was the USB 3.0 port so I tested other USB 3.0 devices. A USB 3.0 flash drive and a different USB 3.0 mechanical drive (a bus-powered Western Digital drive similar to the Seagate but with 500 GB capacity) both work fine. I'm using a "badblocks" test run to hammer away at them for hours, both pass and never unmount.
The USB 3.0 port in question is on the front/top of my case, connected to the USB 3.0 internal header on my Gigabyte GA-990FXA-UD3 motherboard.
I believe that unmounting/remounting could be a sign that the USB bus is not providing enough power to the hard drive, but it worked fine under LM16 and this is USB 3.0 with more power than USB 2.0...and it works fine in a USB 2.0 port.
I'm not sure what help dmesg and syslog would provide, all they seem to indicate is that they're trying to read/write to/from a drive that just dropped off the bus...I/O errors, file system not found, etc. However I'd be pleased to post any log files that may be helpful. SMART data indicate the drive is fine.
Thanks for any assistance.