RACNet is a sensor network that monitors a data center’s environmental conditions at high temporal and spatial resolutions. The data RACNet collects can improve the energy efficiency of data centers, currently one of the fastest growing energy consumers in the U.S. RACNet overcomes the challenge of reliable and low-latency data gathering from dense networks deployed in harsh RF environments through rDCP, a novel network protocol that decouples data collection from topology control. Furthermore, rDCP automatically partitions the network to multiple routing trees, each operating at a different frequency channel. The combination of these features enables rDCP to scale up while maintaining high data yields. Preliminary results from a production deployment of 694 sensors (including 174 wireless nodes) show that rDCP achieves a data yield of 99%, while delivering 90% of the measurements in less than 30 seconds.