I have two disks in my Time Machine set up. The first has 40GB free and the second has 500GB free. Time Machine is trying to back up 90GB. I get the message that the backup failed because the first disk does not have enough free space and yet it does go ahead and use the second disk to backup. This has been going on for a couple of days now. Any suggestions on how I can get rid of the annoying message? I did enter Time Machine and I do see that it is working.