Data centers in the “cloud” will need to support a wide range of applications, each with their own input/output (I/O) requirements. Some applications perform small and random I/O operations, whereas others demand high streaming bandwidth. In addition, in order to reduce costs, cloud data centers will contain thousands of commodity servers and network switches. Delivering high performance with unreliable commodity hardware for this range of workloads is a grand challenge. ZoneFS uses zone-based data striping in data center infrastructures built from commodity network switches. By striping data in zones, ZoneFS reduces network congestion and avoids one or more storage servers from becoming I/O bottlenecks. In this paper, we present the overall design and implementation of ZoneFS and evaluate its key features with several cloud-computing workloads.