WD Backup says not enough space on my 2TB Passport

Trying to backup 1.14TB onto my 2TB My Passport drive using WD Backup but keep getting “Unable to back up files to My Passport because there is not enough space.” This is after reformatting the drive through Windows Disk Management (meaning, the drive is empty). What am I missing?

Hi zSlaughterz,

As WD Backup maintains a second copy of the backup for data recovery purposes so it requires additional disk space for pruning older backups from existing backup plans. For example, If the computer has 1.14 TB of data, WD Backup will need at least 2.28 TB of of external USB storage to create a backup plan.
(1.14 TB + 1.14 TB = 2.28 TB)

You may refer below article for more details: