An apparatus and method for measuring the physical quantities of a data center during operation and method for servicing large-scale computing systems is disclosed. The apparatus includes a cart that supports a plurality of sensors. The cart is moveable within the data center. The sensors capture temperature or other physical parameters within the room. The sensor readings, along with position and orientation information pertaining to the cart are transmitted to a computer system where the data is analyzed to select the optimum temperature or other system environmental parameters for the data center.