100% up-time is the requirement of data center facility performance.
However, failures do occur, even within facilities that have the best preventative maintenance. Data centers are designed with redundant physical equipment and sensors to allow for active failures in the operating environment without affecting uptime performance. Errors in the complex facility control software create an environment that is unpredictable, unstable, or even worse, not redundant. It can also be cost prohibitive to install additional sensors throughout a plant, and oftentimes critical sensors are installed without a physical backup.