US Patent 11120048 Non-disruptive transition to synchronous replication state

Techniques are provided for transitioning a first storage object and a second storage object from an asynchronous replication state to a synchronous replication state. Metadata operations are logged into a metadata log. Dirty data, modified by data operations executed upon the first storage object, are tracked using a dirty region log. Metadata operations are replicated from the metadata log to the second storage object during a metadata drain phase. During the metadata drain phase, incoming operations are logged into the metadata log when the metadata log has a non-zero size, otherwise, the metadata operations are replicated to the second storage object. After the metadata drain phase, a data drain phase is performed using the dirty region log.