Block Allocation in Video Servers for Availability and Throughput

Video servers aimed at the home market must deliver very large files at a low cost. The video files must be shared and reused to contain costs. The nature of videos, however, demand a low jitter (late block delivery) rate. Normal systems tolerate disk queues and deliver, typically, smaller objects in a less predictable manner. This paper explores in a multi disk, stripped, environment whether block placement, interdisk permuation, replication and compression impacts the rate of jitter in a multiuser setting with different assumptions as to the pattern of use. Correspondingly, the number of supportable users for a given level of quality (jitters per hour per user) is addressed. Block allocation is the term used to describe the placement of video blocks on selected disk(s).