Continuous media file server system and method for scheduling network resources to play multiple files having different data transmission rates

摘要

A continuous media file server system has a controller connected to multiple data servers. Each data server supports at least one storage disk. Data files are distributed across the data servers so that data blocks of the data files are stored on each of the storage disks. The data files have different data transmission rates at which they are served over a network to clients in the form of data streams. A scheduling unit maintains a network schedule that provides a relative ordering of transmission times of requested data streams. The transmission times indicate when the data servers are to transmit corresponding data blocks of the requested data files over the network to stream the data to clients. The block play times for all data files have a fixed duration, with the size of the data blocks from data file to data file varying according to the data transmission rates of the files. When a transmission time for a data file block approaches, the scheduling unit instructs the appropriate data server to read a data block for that data file from the disk prior to the transmission time in the network schedule. In this manner, disk reads are scheduled implicitly according to the network schedule. The data is temporarily stored in buffer memory, and later transmitted over the network. When a request for a new data stream is received, the scheduling unit evaluates whether the new data stream can be inserted into the network schedule without overburdening the data servers' ability to serve the existing data streams on the network schedule.