A circular skip-cluster scheme to support video-on-demand services

The major drawback of the existing cluster placement scheme is the long res ponse time caused by admission control if the number of clusters and the nu mber of users are large. A circular skip-cluster placement scheme is propos ed to reduce the size of the data buffer as well as the system response tim e. Furthermore, the popularity of each video is different in the real world . We propose a new popularity-based data allocation scheme to allocate data units within a cluster such that the corresponding data units of these pop ular videos are stored in those cylinders at one end of each cluster. Due t o a higher spatial locality within these hot cylinders, some data units req uested by the users are stored in the same cylinder such that one seek oper ation, one rotation, and one transfer operation are required to retrieve th ese data units. Therefore, the time required to retrieve data for these req uests can be reduced, thus also reducing the system response time. Based on our results, the buffer size and the system response time can be reduced b y half or more. These findings are essential for constructing video-on-dema nd systems that provide satisfactory performance.