Conventional servers have achieved high performance by employing fast CPUs to run compute-intensive workloads, while making operating systems manage relatively slow I/O devices through memory accesses and interrupts. However, as the emerging workloads are becoming heavily data-intensive and the emerging devices (e.g., NVM storage, high-bandwidth NICs, and GPUs) come to enable low-latency and high-bandwidth device operations, the traditional host-centric server architectures fail to deliver high performance due to their inefficient device handling mechanisms. Furthermore, without resolving the architecture inefficiency, the performance loss will continue to increase as the emerging devices become faster. In this paper, we propose DCS, a novel device-centric server architecture to fully exploit the potential of the emerging devices so that the server performance nicely scales with the performance of the devices. The key idea of DCS is to orchestrate the devices to directly communicate with each other while selectively bypassing the host. The host becomes responsible for only few device-related operations (e.g., filesystem lookup). In this way, DCS achieves high I/O performance by direct inter-device communications and high computation performance by fully utilizing the host-side resources. To implement DCS, we introduce DCS Engine, a custom hardware device to orchestrate devices via standard I/O protocols (i.e., PCIe and NVMe), along with its device driver and user-level library. We show that our FPGA-based DCS prototype significantly improves the performance of emerging server workloads and the architecture will nicely scale with the performance of the devices.