PC cluster system is an attractive platform for data-intensive applications. But the conventional shared-nothing system has a limit on load balancing performance and it is dificult to change the number of nodes and disks dynamically during execution. In this paper, we develop dynamic resource injection, where the system can inject CPU power and expand I/O bandwidth by adding nodes and disks dynamically in the SAN(Storage Area Network)-connected PC cluster. Our experiments with data mining application confirm its effectiveness. We show the advantages of combining PC cluster with SAN.