Incremental transfer with unused data block reclamation

A non-transitory machine readable medium having stored thereon machine executable code which when executed by a machine, causes the machine to:

• determine that a transfer utilized a base snapshot of a source volume hosted by a first node for replication of blocks to a destination volume hosted by a second node, where a snapshot of the source volume is deleted after the transfer and a new snapshot of the source volume is created subsequent the transfer;
• identify a set of new blocks, allocated to the new snapshot, to transfer to the destination volume by a subsequent transfer based upon a comparison of a first active map of the base snapshot and a second active map of the new snapshot;
• identify a set of unused blocks, previously allocated to the snapshot, deleted from the source volume based upon a comparison of the first active map and a first summary map of the base snapshot with the second active map and a second summary map of the new snapshot, comprising:
• excluding a block from the set of unused blocks based upon the active and summary maps indicating that the block was unallocated to the base snapshot and allocated to at least one snapshot of the source volume when the base snapshot was captured, and indicating that the block was allocated to the new snapshot when the new snapshot was captured;
• and
• perform the subsequent transfer to transmit the set of new blocks to the second node to write to the destination volume, wherein the subsequent transfer instructs the second node to deallocate the set of unused blocks from the destination volume during execution of the subsequent transfer to write the set of new blocks to the destination volume.

A computing device comprising:

• a memory comprising machine executable code;
• and
• a processor coupled to the memory, the processor configured to execute the machine executable code to cause the processor to:
• determine that a transfer utilized a base snapshot of a source volume hosted by a first node for replication of blocks to a destination volume hosted by a second node, where a snapshot of the source volume is deleted after the transfer and a new snapshot of the source volume is created subsequent the transfer;
• identify a set of new blocks, allocated to the new snapshot, to transfer to the destination volume by a subsequent transfer based upon a comparison of a first active map of the base snapshot and a second active map of the new snapshot;
• identify a set of unused blocks, previously allocated to the snapshot, deleted from the source volume based upon a comparison of the first active map and a first summary map of the base snapshot with the second active map and a second summary map of the new snapshot, comprising:
• identifying a block for further evaluation during a subsequent incremental transfer based upon the active and summary maps indicating that the block was unallocated to the base snapshot and allocated to at least one snapshot of the source volume when the base snapshot was captured, and indicating that the block was unallocated to the new snapshot and allocated to at least one snapshot of the source volume when the new snapshot was captured;
• and
• perform the subsequent transfer to transmit the set of new blocks to the second node to write to the destination volume, wherein the subsequent transfer instructs the second node to deallocate the set of unused blocks from the destination volume during execution of the subsequent transfer to write the set of new blocks to the destination volume.