A method is provided method for allocating storage space. The method includes obtaining performance parameters for a storage pool, wherein the performance parameters comprise a size of the storage pool and a type of the storage pool. Proposed back end logical units (BELUs) to match the performance parameters are determined. Current disk groups for the proposed BELUs are identified, and if none exists, a plurality of storage arrays is analyzed to locate free disks that can be formed into a proposed disk group to support the creation of the proposed BELUs. A proposal is created showing the changes that would be made to a storage system to create the storage pool.