A data rebalance control system determines instruction contents for an entity having a rebalance function, based on the capacity information including information indicating a plurality of physical capacities corresponding to a plurality of storing devices which include at least one storing device having a compression function, coupled to one and more computers included in a computer system. The rebalance function of the entity is a function of rebalancing data so that the distribution of the plural logical capacities recognized by the entity, corresponding to the plural storing devices, may be a predetermined distribution. The determined instruction contents include a definition about the logical capacity distribution. The data rebalance control system transmits, to the entity, a rebalance instruction as an instruction to rebalance the data according to the above instruction contents.