At the design of the video server to service video data as real-time, we must consider network bandwidth, buffer space and disk bandwidth. As buffer space and disk bandwidth affect each other tightly, they should be considered at the same time.In this paper, we propose the hard real-time tasks' model for the streams on the video server. The stream on the server can be considered as the hard real-time task in that the server must guarantee the continuity of streams as if the hard real-time system must guarantee the deadline of tasks. The management of streams in the server is induced from the scheduling of real-time tasks.We propose hard read-time tasks models for the video server and the scheduling algorithms for real-time tasks. The real-time scheduling algorithms are used for admission control of streams, scheduling of disk, and management of buffers in video server. We design the effective video server using the real-time task model. We evaluate the performance of our suggested video server via a proper simulation. We show that our mechanism can service more streams with a few buffers simultaneously.