A method and apparatus for increasing the number of storage units. Specifically, the present invention describes a method for creating a plurality of virtual logical units (LUN) of storage from a plurality of existing volumes of storage for access by a plurality of host applications via a virtualization layer. The virtual LUNs are created by partitioning the existing volumes into a plurality of slices. Each of the plurality of slices is then mapped to the plurality of virtual LUNs. Furthermore, each of the plurality of virtual LUNs is masked to each of the plurality of host applications to provide access control. The plurality of host applications are transparently interfaced to the existing volume while preserving the original configuration of internal operating code or intelligence for interfacing with the plurality of existing volumes.