We propose to use Fibre Channel (FC) technology in multimedia systems offering Video on Demand (VoD) services. The Storage Area Network (SAN) is based on (i) FC-loops connecting magnetic disks and on (ii) FC-switches connecting loops to servers. We show how to dimension FC-loops to offer a deterministic guarantee of Quality of Service to the VoD clients. The performance results of this analysis, confirmed by already published simulation results, enable to determine the optimal number of disks connected to a loop and the maximum number of clients acceptable by a loop. We study the influence of disk performance and determine the best number of blocks to retrieve per disk request.