I was attempting to use my 8TB WD Passport for my Time Machine backup and was told I couldn’t use it until I cleared all the data off the drive. I thought this was not correct (I should have trusted my gut), but did it anyway. Now I can’t use if for backup. I can see it in disk utility, and have run First Aid, but it keeps saying I need to run First Aid from Recovery. Tried that, but no dice. The Details section states “Problems were found with the partition map which might prevent booting.” I also looked at Restore, but I’m not sure what this does so I don’t want to screw it up anymore. Please help! 
Hello,
Have you tried formatting the drive?
There is no such thing as an 8TB Passport.
Erase your hard drive correctly and it should work properly.
Well excuuuuuuuuse me!
He is right though.
https://www.wdc.com/en-um/products/portable-storage.html
Usually, a larger-than-actual hard drive size is a sign of a hardware failure when coupled with the error messages in Disk Utility.
How did you format your hard drive? Did you select GUID Partition Table with Mac OS Extended (Journaled), or did you select a different configuration?
