> Can someone please, pretty please with sugar on top, explain > the point behind high power density?
It allows you to market your operation as a "data center". If you spread it out to reduce power density, then the logical conclusion is to use multiple physical locations. At that point you are no longer centralized. In any case, a lot of people are now questioning the traditional data center model from various angles. The time is ripe for a paradigm change. My theory is that the new paradigm will be centrally managed, because there is only so much expertise to go around. But the racks will be physically distributed, in virtually every office building, because some things need to be close to local users. The high speed fibre in Metro Area Networks will tie it all together with the result that for many applications, it won't matter where the servers are. Note that the Google MapReduce, Amazon EC2, Haddoop trend will make it much easier to place an application without worrying about the exact locations of the physical servers. Back in the old days, small ISPs set up PoPs by finding a closet in the back room of a local store to set up modem banks. In the 21st century folks will be looking for corporate data centers with room for a rack or two of multicore CPUs running XEN, and Opensolaris SANs running ZFS/raidz providing iSCSI targets to the XEN VMs. --Michael Dillon