Cloud-based distributed data storage system using block-level deduplication based on backup frequencies of incoming backup copies

A method for providing deduplication with block-level expiry granularity in a cloud-based distributed data storage system, the method comprising:

• in a first cloud computing environment comprising a first storage service node that hosts a metadata subsystem of the distributed data storage system, and further comprising a second storage service node that hosts a data storage subsystem of the distributed data storage subsystem, wherein a system-wide deduplication virtual disk is distributed across a plurality of storage service nodes of the distributed data storage system, including the second storage service node, and wherein the system-wide deduplication virtual disk stores deduplicated data blocks:
• by the metadata subsystem at the first storage service node, assigning an expiry timeframe to a first unique system-wide identifier (the first DDblockID), wherein the first DDblockID is associated with a first data block stored in the system-wide deduplication virtual disk,
• wherein the expiry timeframe is based on:
• an arrival timeframe of the first data block at the distributed data storage system, and spans a full backup frequency configured for a first user virtual disk addressed by a write request comprising the first data block, wherein the first user virtual disk is distinct from the system-wide deduplication virtual disk;
• and
• by the metadata subsystem executing a discard cycle:
• determining that a second data block, which was received in a second write request addressing a second user virtual disk and which arrived at the distributed data storage system after a preceding discard cycle, has a same hash value as the first data block,
• associating the second data block with the first DDblockID based on the same hash value, and
• extending the expiry timeframe of the first DDblockID to span a sparsest full backup frequency of all user virtual disks referencing the first DDblockID, including the first user virtual disk and the second user virtual disk.