Patent US 11,620,064

Techniques are provided for asynchronous semi-inline deduplication. A multi-tiered storage arrangement comprises a first storage tier, a second storage tier, etc. An in-memory change log of data recently written to the first storage tier is evaluate to identify a fingerprint of a data block recently written to the first storage tier. A donor data store, comprising fingerprints of data blocks already stored within the first storage tier, is queried using the fingerprint. If the fingerprint is found, then deduplication is performed for the data block to create deduplicated data based upon a potential donor data block within the first storage tier. The deduplicated data is moved from the first storage tier to the second storage tier, such as in response to a determination that the deduplicated data has not been recently accessed. The deduplication is performed before cold data is moved from first storage tier to second storage tier.