I think that the files are old Time Machine back ups.
Mac Pro, OS X 10.11
Or you can just start another drive as an ADDITIONAL backup set, without removing the old one. Time machine will create a new stand-alone backup on the new drive starting from today, and every-other backup will go to every-other drive until you re-configure.
You should never ever move Time Machine backups to the Trash.
The way to fix the problem, is to erase your Time Machine backup drive and start over with new backups.
That's what I was trying to escape...
Thanks for the advice.
You could also eject, disconnect and set that external drive aside, then start Time Machine backups on another external drive.
Thank you all for the guidance, I am going to get a 2nd 1TB external.
it's not a lot more money to buy a drive that is a bit larger.
Thanks, I will look around.
I can't delete the trash, I get error message that "items are in use"
