  In a distributed storage system, the storage costs of different storage
nodes, in general, can be different. How to store a file in a given set of
storage nodes so as to minimize the total storage cost is investigated. By
analyzing the min-cut constraints of the information flow graph, the feasible
region of the storage capacities of the nodes can be determined. The storage
cost minimization can then be reduced to a linear programming problem, which
can be readily solved. Moreover, the tradeoff between storage cost and
repair-bandwidth is established.
