gregrwm cried from the depths of the abyss...

> 
> what fs? 

ext4

>  btrfs et al have features that could be holding on to the 
content.
> 
> what sort of backups?  BackupPC et al keep hardlinks to everything.  you can explore what's allocated with du..

The directory contained 5 backpus of the content of our email archiving 
server (mirapont razor safe 170).

I have check using du with the --max-depth=1 option to keep it easy to 
read, and the totals don't add up?