I was working in 2 racks, with 2 different systems. One in production, the other was being commissioned. I went to the back of the racks, to turn off the ones being commissioned, but counted wrong (long aisle of racks) ans turned off the production rack. There where 12 servers, 10 Front end and middleware, and 2 backends with an Oracle 10… I was white as snow from the shock. I was escorted outside of the datacenter, and given water. The pals with me thought I would collapse.