The IT industry is the fastest growing sector in US energy
consumption. Improving data center energy efficiency
is a pressing issue with significant economic and environmental
consequences. Heat distribution is a key operational
parameter that affects data center cooling and energy consumption.
However, typical data centers lack effective finegrained
sensing systems to monitor heat distribution at a
large scale. In this paper, we motivate the use of sensor networks
as a dense instrumentation technology to understand
and control cooling in data centers. We present Microsoft
Research Genomote sensors designed for data center monitoring,
and the RACNet for reliable data acquisition. We
describe lessons learned from early pilot deployments, and
discuss architectural and technical challenges in developing
data center sensor networks.