3. RDISK node

Figure 5 shows the block diagram of an RDISK node. The heart of the system is based on a low-cost reconfigurable component, a Spartan II from Xilinx. Once configured, this component controls the various elements of the board, as well as filtering data during a query.

• A microcontroller takes care of initializing the node on power-up, as well as reconfiguring the FPGA. More precisely, at start-up, the microcontroller downloads a bitstream from the hard disk, ensuring the node's minimal functionality: data reads and writes via the Ethernet connection. Once this task has been completed, it hands over to the FPGA and goes into stand-by mode. When a request is made to download a new bitstream, the microcontroller is reactivated by the FPGA, which tells it the number...