DYNAMICALLY UPGRADEABLE DISK ARRAY SYSTEM AND ORTHOGONAL SIGNAL MULTIPLEXING SYSTEM THEREFOR

摘要

A dynamically upgradeable disk array chassis (10), a method for dynamically upgrading a data storage system, diplexed computer communications and a diplexer (50) wherein the diplexer (50) and the diplexed communications may be used in the dynamically upgradeable disk array chassis (10). The dynamically upgradeable disk array chassis (10) includes a serial bus (22) having a first bus for passing data in one direction and a second bus (24) for passing data in the opposite direction. A shunt (40) connects the first (22) and second (24) buses in a normal state. The shunt (40) has a switched state in which each of the first and second buses is coupled to a separate output from the chassis. The chassis (10) includes an environmental monitor (30) connected to a communication path (42). Upon connecting a new disk array chassis to an active disk array chassis, the environmental monitor (30) communicates through the communication path (42) before switching the shunt (40) to connect the serial bus with the serial bus of the new disk array chassis. The disk array chassis (10) may include a diplexer (50) for connecting the communication path (42) to the separate outputs of the shunt (40) and for combining the communicaton path signals with the serial path signals in one direction and for separating these signals in the other direction. The diplexer (50) may include an adder for adding the signals from the communication path with those on the serial path and a subtractor for subtracting signals of one path from the other. The environmental monitor path communications and the serial bus communications can take place over a single twinax cable (18). One signal is differentially coupled onto a first pair of conductors. A second signal is common mode coupled onto the first pair of conductors. In the opposite direction on the twinax cable (18), different signals are also differentially coupled and common mode coupled to the return pair of conductors.