Designing a scalable video-on-demand server with data-sharing

As current disk space and transfer speed increase, the bandwidth between a server and its disks has become critical for Video-On-Demand (VOD) services. Our VOD server consists of several hosts sharing data on disks through a ring-based network. Data sharing provided by the spatial-reuse ring network between servers and disks not only increases the utilization towards full bandwidth but also improves the availability of videos. Striping and replication methods are introduced in order to improve the efficiency of our VOD server system as well as the availability of videos. We consider two kinds of resources(disk space, and bandwidth) of a VOD server system. Given a representative access profile, our intention is to propose an algorithm to find an initial configuration, place videos on disks in the system successfully. If any copy of a video cannot be placed due to lack of resources, more servers/disks are added. When all videos are placed on the disks by our algorithm, the final configuration is determined with indicator of how tolerable it is against the fluctuation in demand of videos. Considering it is a NP-hard problem, our algorithm generates the final configuration with O(M log M) at best, where M is the number of movies.