A great number of scientific applications that access to a large amount of data have emerged last few years. For example in high energy physics, the volume of data will be measured in petabytes in the next years. Grids seek to aggregate geographically distributed resources for the need of these applications. It results that scientists have to deal with many problems to manage available data over the grid. Since grid resources are interconnected by WAN, the main speculation is that data transfers over the grid are bounded by network latency and bandwidth. Here, we point out some storage device issues which in many cases invalidate this assumption. Implicitly, we give a new direction that will lead to a better utilization of available resources on a grid