Memory-efficient metadata organization in a storage array

Abstract

A metadata tree structure having a plurality of nodes (slabs), each node containing a MD table. Each of the MD tables has a plurality of entries. Each of the entries in the MD tables represents a contiguous range of block addresses and contains a pointer to a cache slot storing a date block corresponding to the block address, or an indicator to indicate that the corresponding data block is not stored in a NVRAM cache slot. Each MD table also contains a block address range indicator to indicate the contiguous range of block addresses, and at least one pointer to point to any parent or child nodes. In an alternative embodiment, the pointer of each MD entry may point to a disk address if the data is not in cache. For such an embodiment, portions of the MD store may be stored to disk.