A mechanism is provided in a data processing system for asynchronous replication. The mechanism creates a record in a write log in a host computing device for a write command and marking the record as uncommitted. The mechanism maintains a copy of data to be written by the write command at the host computing device. The mechanism issues the write command from the host computing device to a primary storage controller at the primary storage site. Responsive to receiving an acknowledgement from the primary storage controller that the data have been written to the primary storage site, the mechanism marks the record as unreplicated. Responsive to receiving an acknowledgement from the primary storage controller that the data have been replicated to a secondary storage site, the mechanism erases the record in the write log and deleting the copy of data.