This is a 120 page document describing the design of state of the art, large scale computing facilities, such as those run by the big Internet companies. It discusses everything from facilities issues through the computing hardware through to the software infrastructure. This is an excellent design guide about how everyone should be designing data centers of all sizes, not just huge facilities. Don't be intimidated by its length: it is very easy to read. Just browse the table of contents and pick and choose the sections that interest you. I particularly enjoyed Chapter 5: Energy and Power Efficiency.
L. A. Barroso and U. Hölzle. The Datacenter as a Computer: An Introduction to the Design of Warehouse-Scale Machines, M. D. Hill, Ed. San Rafael, CA, USA: Morgan & Claypool, 2009.