The Belle experiment operates at the KEKB accelerator, a high luminosity asymmetric energy e+ e- collider. The Belle collaboration studies CP violations in decays of B mesons to answer one of the fundamental questions of Nature, the matter-anti-matter asymmetry. Currently, Belle accumulates more than one million B Bbar meson pairs, corresponding to about 1.2 TB of raw data, per day.The challenge is how to realize the required high performance data access and scalable data computing. The Gfarm file system is a Grid-wide network shared file system that federates local storage of cluster nodes; moreover it provides scalable I/O performance with distributed data access. In the challenge, we will construct a Gfarm file system with 40 TB capacity and 30 GB/sec I/O bandwidth, integrating the local disks of 800 compute nodes in the KEKB computing facility, and demonstrate high-performance Belle data analysis.