We present LiveRAC, a visualization system that supports the analysis of large collections of system management timeseries data consisting of hundreds of parameters across thousands of network devices. LiveRAC provides high information density using a reorderable matrix of charts, with semantic zooming adapting each chart's visual representation to the available space. LiveRAC allows side-by-side visual comparison of arbitrary groupings of devices and parameters at multiple levels of detail. A staged design and development process culminated in the deployment of LiveRAC in a production environment. We conducted an informal longitudinal evaluation of LiveRAC to better understand which proposed visualization techniques were most useful in the target environment. ACM Classification Keywords H.5.m Information Interfaces and Presentation: Miscellaneous General Terms Design, Human Factors Author Keywords visualization, time-series data, longitudinal studies