Determining the size of a WHM backup is not entirely straightforward. For example, it’s not displayed in the daily report or in the UI. The reason for this might be that determining disk size in Linux takes time and disk IO and running this as an extra process might cause a performance issue Additionally if you have large backups, and you’ve opted for the incremental option, you have tens of thousands of files on the disk meaning determining the size takes even longer.
If you’re happy to keep your disk busy for the next 11 minutes, then do the following in the backup directory.
[root@server04 2020-07-01]# du -h --max-depth=1 # Wait for 11 minutes 955M ./system 189G ./accounts