Actually that is a picture taken at the Tulare World AG Expo in California. It is a picture of my brother who is 6' 2" and gives a perspective of just how big this thing is. 40" disk pans, 1/2" thick.
And people say that disks are not for major ground tillage and that they are not used any more.

These types of disks take a wee bit bigger than a 50-60hp tractor to even move. I assume that with as many venders of these that there are at the Expo, that this type of tillage is still done in many places.