Abstract: A client-configurable tiering service implements an interface allowing a client to specify a tiering policy selected from a plurality of supported tiering policies for data of the client stored in a warm tier, wherein the tiering policies specify conditions for relocating portions of the data to a cold tier. The interface also allows a client to specify a tombstone forwarding policy selected from a plurality of supported tombstone forwarding policies, wherein the tombstone forwarding policies specify how data relocated from the warm tier to the cold tier is subsequently retrieved in response to an access request directed to the warm tier. The client-configurable tiering service relocates and retrieves data between a warm tier and a cold tier in accordance with the client's selected policies. In some embodiments, a client may specify further aspects of how data is stored and relocated between different tiers of a data store.