A method, apparatus, and computer program product for reclaiming one or more chunks in a snapshot storage space, are disclosed. The method comprises detecting one or more unused chunks in the snapshot storage space in response to a predefined trigger event, and reclaiming one or more detected unused chunks by providing the one or more detected unused chunks to a storage pool for reuse. One or more unused chunks may be detected by scanning a first mapping table that records a storage state of a plurality of chunks in the snapshot storage space, and a determination made whether the one or more detected unused chunks have been reclaimed. If the one or more detected unused chunks have not been reclaimed, the one or more detected unused chunks may be provided to the storage pool and a second mapping table updated to record a reclaiming state of the one or more unused chunks. A new snapshot may be stored using a chunk in the snapshot storage space that has not been used and has not been reclaimed yet.