Data migration method and system

The invention discloses a data migration method which comprises the following steps that: data shift-out nodes are notified to carry out data migration according to the user selection; the data shift-out nodes directly send migration data and redo log to data shift-in nodes; the data shift-in nodes receive and store the migration data and receive the redo log for checking and updating the received migration data according to the redo log. The invention also discloses a data migration system. When the method and the system disclosed by the invention are adopted, the data migration speed can be improved while the normal work of the system is ensured, and the data consistency in the migration process can be ensured.