A scalable hierarchical video storage architecture

Lancaster University is investigating the design of a scalable hierarchical video storage architecture, which can support the replay of tens of simultaneous video and audio streams to clients distributed around the campus and wide area. The project aims to address the bandwidth problems of single node video servers, by providing multiple storage instances with streams load balanced across the instances. Two differing methods of load balancing have been investigated: file replication; and node striping. To reduce the overhead of file replication redundancy and to minimise the reliability problems of simple node striping, a two level distribution hierarchy consisting of domains is introduced. A domain consists of a collection of storage nodes distributed over a LAN, using node striping, where the overall reliability of the network is high. Between domains, file replication is used, with file interests (popularity) and network link capabilities being used to control overall file replication and placing. Such a hierarchy is highly scalable, enabling a VoD system to be scaled over both the local and wide area. The approach is investigated through simulation and an implementation.