You can manually pause the volume move during the setup phase or the data copy phase to complete any high priority I/O operations.
system1> vol move pause vol1 Wed Aug 29 08:11:40 GMT [system1: replication.src.err:error]: SnapMirror: source transfer from vol1 to system1: ndm_dstvol_1188375081 : transfer failed. Wed Aug 29 08:11:41 GMT [system1: replication.dst.err:error]: SnapMirror: destination transfer from 127.0.0.1:vol1 to ndm_dstvol_1188375081 : replication transfer failed to complete. Wed Aug 29 08:11:41 GMT [system1: vol.move.paused:info]: Move of volume vol1 to aggregate aggr1 paused : User initiated