Abstract: A write lock request for a data object on behalf of a first data accessor is received at a lock manager. The data object is currently locked on behalf of a second data accessor. The lock manager modifies lock metadata associated with the data object to indicate the first data accessor as the primary lock owner, and designates the second data accessor as a non-primary owner.

Abstract: A write lock request for a data object on behalf of a first data accessor is received at a lock manager. The data object is currently locked on behalf of a second data accessor. The lock manager modifies lock metadata associated with the data object to indicate the first data accessor as the primary lock owner, and designates the second data accessor as a non-primary owner.

Abstract: Methods, systems, and computer-readable media for live migration for highly available data stores are disclosed. Migration of a data set from a first data store to a second data store is initiated and comprises a backfill of records to the second data store. During a window of time before the migration is complete, a read request for a first record is received. A response representing an authoritative version of the first record is generated using a copy of the first record in the first data store and a copy of the first record in the second data store. A write request for a second record is received during the window of time. A lock is acquired for the second record, and the write request is performed using a copy of the second record in the first data store and a copy of the second record in the second data store.

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.