Time Machine drives "ejected" during backup
I have two Time Machine drives. One connected to the MacBook Pro 15 USB port. The other connected to an attached Cinema Display. Both drives started failing at backup about a month ago. The error is that the drive was ejected. The .inProgress file gets partially built, up to maybe 2GB.
Have restarted, safe booted, swapped ports, reformatted one drive.
They still claim to have been ejected, but the drives always remain mounted.
Has anyone discovered the cause of this? -Thanks
MacBook Pro Retina