We present a multimedia server comprising of multiple stream controllers connected to a host (work station) I/O bus. Each stream controller manages an array of disks in which multimedia data is stored in format of network packets. When the host instructs the stream controller to deliver a multimedia file to a client, the stream controller retrieves the network packets of that file, completes the missing header/trailer fields, and forwards these packets to the network interface directly, avoiding any further involvement of the host. To avoid interference on the disks, data is interleaved across all disks connected to a stream controller in fixed play back time units. This helps reduce the jitter in the response time of the disks, and therefore, the size of the buffers needed to maintain interruption free delivery. Metadata is stored with the network packets of a video/multimedia file to enable the stream controller to autonomously fetch a complete multimedia/video file without host intervention. In a departure from traditional RAID, the stream controller simultaneously issues a set of read commands periodically, one for each active multimedia stream. Each read command retrieves a full interleave unit from a single disk, and the set of simultaneously issued read commands are distributed across all disks.
By: Manoj Kumar, Jack L. Kouloheris, Mary J. McHugh and Sneha Kasera (Univ. of MA at Amherst)
Published in: RC20059 in 1995
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