Abstract: A storage medium unit for recording of storing data, wherein the data are divided in a predetermined number of data groups, wherein the first portion of the data groups are memorized on every N (N=1, 2, 3, . . . ) track of a recording medium and the remaining portions of the data groups are memorized on remaining tracks of the recording medium.

Abstract: A system for serving information includes a router; archive storage medium units connected to the router for storing information data; delivere storage medium units connected to the router for partially storing information data from the archive storage medium units; end devices each having an input and a display connected to the router for outputting demand data requesting selected information data; and a controller connected to the router for managing distribution of the information data.

Abstract: A system for serving video and/or audio data includes one or more first storage medium units for storing video and/or audio data, and at least one second storage medium unit with an agile disc for storing the video and/or audio data. A controller downloads a software control program to the first and second storage units. A plurality of end devices each have input means and display means for reproducing video and/or audio data from the storage medium units. A system manager manages distribution of the control software program and the audio/video data. The system manager receives demand data representing information regarding audio/video data selected by a user and a demanded operation mode, and outputs distribution control data including channel information of the selected audio/video data, the operation mode and routing information, to the end device.