A high-performance data acquisition (DAQ) system has been developed for steady-state fusion experiments at the Large Helical Device (LHD). Its significant characteristics are 110 MB s−1 continuous DAQ capability and the performance scalability using an unlimited number of DAQ units. Incoming data streams are first transferred temporarily onto the shared random access memory, and then cut into definite time chunks to be stored. They are also thinned out to 1/N to be served for the real-time monitoring clients. In LHD steady-state experiment, the DAQ cluster has established the world record for acquiring 90 GB/shot. The established technology of this steady-state acquisition and store can contribute to the ITER experiments whose data amount is estimated in the range 100 or 1000 GB/shot. This system also acquires experimental data from multiple remote sites through the fusion-dedicated virtual private network in Japan. The speed lowering problem in long-distance TCP/IP data transfer has been improved by the packet pacing optimization. The demonstrated collaboration scheme will be analogous to that of ITER and the supporting machines.
The LABCOM data acquisition system (DAQ) has set a new world record of acquired data amount of 90 GB/shot in 2005-2006 campaign. Its CompactPCI-based new DAQ enables about 80 MB/s real-time acquisition for each plasma measurement. The basic performance of a DAQ unit has already good prospects for the next-generation fusion experiments, however, some surrounding utilities are not necessarily developed to construct tentimes larger DAQ system yet. The increasing number of parallel DAQ units has made the operational and maintenance burden very heavy. So, "more distributed acquisition and centralised operations" would become expected. Here, DAQ front-end consisting of some digitizer chassis, a timing module, and an acquisition computer has been entirely re-designed to realize a lower-cost and maintenance-free "DAQ Box" for fusion plasma measurements. OS and softwares have been also remodelled to use free drivers on Linux. Network-bootable diskless computers are also desirable for reducing the possibility of hardware troubles, and it simultaneously realizes to omit first-tier data storage and reduce the migration operational cost. As a result, total hardware cost could be reduced almost one fifth than the previous. This could be the way to realize ten-times larger fusion experiment in the near future.
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