1. A method for allocating storage space, comprising: determining one or more proposed back end logical units (BELUs) to match selected performance parameters for a storage pool, wherein the selected performance parameters comprise a size of the storage pool and a type of the storage pool; identifying a current disk group that can support the proposed BELUs; and, if no current disk group can support the proposed BELUs: analyzing a plurality of storage arrays to locate free disks that can be formed into a proposed disk group to support the proposed BELUs; and creating a proposal showing the changes that would be made to a storage system to create the storage pool.