Patent attributes
A backup management system may include a data management server, a warm-tier data store, and a cold-tier data store. Snapshots may be captured from various client devices. A data block stored in the warm-tier data store may be referenced by multiple backup snapshots and/or referenced by one or more users. When a data block's total reference count is equal to the cold reference count or equal to or less than a threshold total reference count, the data management server may determine that the data block is ready to be migrated to the cold-tier data store. The data management server may send the data block into a candidate queue. In the queue, data blocks with similar retention periods or similar expected restoration may be grouped as a unit. The unit may be transmitted to the cold-tier data store in a single write request.
