From
http://216.239.57.104/search?q=cache:kVfI1Wb2qmIJ:www.computer.org/micro/mi…
"To provide sufficient capacity to handle query traffic, our service
consists of multiple clusters distributed worldwide. Each cluster has
around a few thousand machines, and the geographically distributed setup
protects us against catastrophic data center failures (like those arising
from earthquakes and large-scale power failures). A DNS-based
load-balancing system selects a cluster by accounting for the user’s
geographic proximity to each physical cluster. The load-balancing system
minimizes round-trip time for the user’s request, while also considering
the available capacity at the various clusters."
Sounds like they're running a sort of Super Sparrow as well...
Some strange pics:
http://backrub.nerisoft.com/May1998/hardware.htm
--
Gabriel Wicke