FILE SYSTEM VIRTUALIZATION AND SERVICE FOR GRID DATA MANAGEMENT 1. INTRODUCTION Computations are ing increasingly larger scale, in terms of both size and geographical and administration distribution. Examples include scientific grids [1] which harness resources among several institutions for coordinated problem solving, and enterprise information systems that aggregate eforts from multiple sites for collaborative development. Common in these systems is that applications and data are distributed on resources across administrative boundaries and wide-works. Such environments can be referred as the "grid-style" environments, which have the following distinctive characteristics: Heterogeneity: There exist a wide variety of applications and resources in a grid-style environment. The resources typically have diferent hardware configurations (., CPU speed and architecture, memory size, disk bandwidth and capacity) and software setups (., operating systems and libraries); the applications also have diverse characteristics (., data access pattern) and needs (., desired data access performance, security, and reliability). Dynamism: Systems deployed in a grid-style environment are highly dynamic. Failures on machines works can happen at any time, and non-dedicated resources may dynamically join and leave the system. On the other hand, applicat
