This invention relates to data input/output apparatus and the like, which are suitable to be applied to an AV server. As nonlinear accessible storage medium, there is provided with HDD array device (13). When a controller (11) of an AV server (10) receives a command for reproducing data from a minimum of two discontinuous areas in the HDD array device (13) in a first order, the HDD array device (13) then puts the command in an order such that a period of time for access is minimal to reads the data so that the read data are rearranged in the first order to be outputted through decoders (15) to (18). Thereby, the efficiency of data transfer is improved without complications.

A data transmission apparatus having unit modules connected in cascade in a plurality (x; 2.ltoreq.x) of stages and a list converting means, wherein each of the unit modules has a recording and/or reproducing means, a first-list generating means for generating a first list indicating the data to be recorded in the recording and/or reproducing means, a second-list receiving means for receiving a second list indicating the data to be reproduced from the recording and/or reproducing means, and a data supplying means for supplying the reproduced data to the next stage unit module; the recording and/or reproducing means of each of the unit modules records the data indicated in the first list generated by the first-list generating means among the data supplied from the outside and reproduces the data indicated in the second list received at the second-list receiving means; and the list converting means converts a first list generated by a first-list generating means of a y(2.ltoreq.y.ltoreq.x)th stage unit module to a second list and outputs the same to the second-list receiving means of all unit modules or some unit modules of the (y-1)th stage.

In many computer systems, the rate of data from an input source may become significantly faster than a processor's ability to respond. This situation occurs when a faster and more modern system writes to an older and slower legacy system. The result of this interaction between disparate capacity systems may be system failure or data corruption, particularly due to overloading the slower system's input queue to the point where it can no longer catch up to its workload. The invention provides a method, system, and computer-readable medium having computer-executable instructions for transferring data between disparate capacity systems. The method comprises the steps of receiving transactions from a first computer system at a first rate and providing the transactions to a second computer system, wherein the second computer system receives the transactions at a second rate. The second computer system may be a database legacy database server and the first computer system may be an updated database server The second rate is set at a capacity of the second computer system. The method further delays for a predetermined period of time the transactions when the first rate exceeds the second rate. The predetermined period of time is a function of the second rate.