The effect of the storage layer on the writeability of a magnetic head for perpendicular recording was studied through micromagnetic and finite-element-method modeling. The results suggest that the permeability of the storage layer of double-layer perpendicular recording medium monotonically increases with the intergranular exchange. Increase of the storage layer permeability improves the writeability of the single-pole recording head and the gradient of the write field in the storage layer.