Abstract: A data storage system that stores data has a logical address space divided into ordered areas and unordered areas. Retrieval of storage system metadata for a logical address is based on whether the address is located in an ordered area or an unordered area. Retrieval of metadata regarding addresses in ordered areas is performed using an arithmetic calculation, without accessing a block storage device. Retrieval of metadata regarding addresses in unordered areas is performed using lookup tables. In some embodiments, a mixture of ordered and unordered areas is determined to permit the data storage system to store its lookup tables entirely in volatile memory.

Abstract: A block-level storage system and method support asymmetrical block-level redundant storage by automatically determining performance characteristics associated with at least one region of each of a number of block storage devices and creating a plurality of redundancy zones from regions of the block storage devices, where at least one of the redundancy zones is a hybrid zone including at least two regions having different but complementary performance characteristics selected from different block storage devices based on a predetermined performance level selected for the zone. Such “hybrid” zones can be used in the context of block-level tiered redundant storage, in which zones may be intentionally created for a predetermined tiered storage policy from regions on different types of block storage devices or regions on similar types of block storage devices but having different but complementary performance characteristics.