A system, method, and computer-readable storage medium for mapping block numbers within a region to physical locations within a storage system. Block numbers are mapped within a region according to a fractal-based space-filling curve. If the region is not a 2k by 2k square, then the region is broken up into one or more 2k by 2k squares. Any remaining sub-region is centered within a 2k by 2k square, the 2k by 2k square is numbered using a fractal-based space-filling curve, and then the sub-region is renumbered by assigning numbers based on the order of the original block numbers of the sub-region.