Disappearing files On raid 1 setup after backup

This seems to be happening after a backup its a fairly large directory with lots of files

But the directory is their but empty both on the main and the backup disk

Backup disk is a Usb hdd disk.

On the backup disk I have a $History directory that was created and the messed up directory is listed in that folder

As this is a new setup for testing before stuff is totally migrated

I had to shut it off late yesterday did that from web interface When I booted the next day it started backing up I did not do anything with the computer during that time.

From what I can tell everything else is ok 500g of data. (but how can i be sure)

Note: from disk usage that hasnt changed so I think the files maybe still their just not showing up on raid1