Efficient metadata in a storage system

A method implemented in a storage system to support a data movement process, said storage system comprising a persistent storage medium, a memory, a first metadata table comprising a plurality of entries, each of which maps a data block's LBN to its unique content ID, a second metadata table comprising a plurality of entries, each of which maps a unique content ID to its PBN on the storage medium, said method is characterized by:

• reading the data block from its current physical location PBN A;
• determining the unique content ID of the data block;
• looking up the content ID in the second metadata table;
• writing the data block to its new physical location PBN B;
• mapping the content ID to PBN B in the second metadata table;
• and marking PBN A free on free block list;
• wherein the first metadata table entry only includes the data block's content ID but not its LBN;
• wherein the LBN can be a determined based on the metadata entry's relative position in the first metadata table.

A storage system configured to support storage virtualization, data services, and data mobility, comprising:

• a persistent storage medium;
• a memory;
• a first metadata table comprising a plurality of entries, each of which maps a data block's LBN to its unique content ID;
• a second metadata table comprising a plurality of entries, each of which maps a unique content ID to its PBN on the storage medium;
• and
• a storage processor configured to perform a data movement process, wherein as part of the data movement process, the storage controller is configured to:
• read the data block from its current physical location PBN A;
• determine the unique content ID of the data block;
• look up the content ID in the second metadata table;
• write the data block to its new physical location PBN B;
• map the content ID to PBN B in the second metadata table;
• and
• mark PBN A free on free block list;
• wherein the storage processor is further configured to reduce the size of the first metadata table by:
• storing only the content ID of a data block in the data block's entry in the first metadata table, wherein the data block's LBN is determined from the entry's relative position in the first metadata table;
• and
• deduplicating metadata blocks, wherein a plurality of entries in the first metadata table that include only data blocks' content IDs are stored in a metadata block and wherein a unique content ID is generated for each metadata block and metadata blocks are deduplicated based on their unique content IDs.