NDB Cluster Replication: Bidrectional and Circular Replication Figure 23.37 NDB Cluster Circular Replication Where Not All Sources Are Replicas In this case, different SQL nodes in each cluster are used as replication sources and replicas. You must not  start any of the SQL nodes with the  log_slave_updates  system variable enabled. This type of circular replication scheme for NDB Cluster, in which the line of replication (again indicated by the curved arrows in the diagram) is discontinuous, should be possible, but it should be noted that it has not yet been thoroughly tested and must therefore still be considered experimental. Using NDB-native backup and restore to initialize a replica cluster.  When setting up circular replication, it is possible to initialize the replica cluster by using the management client  START BACKUP command on one NDB Cluster to create a backup and then applying this backup on another NDB Cluster using  ndb_restore . This does not automatically create binary logs on the second NDB Cluster’s SQL node acting as the replica; in order to cause the binary logs to be created, you must issue a  SHOW TABLES statement on that SQL node; this should be done prior to running  START REPLICA | SLAVE . This is a known issue. Multi-source failover example.   In this section, we discuss failover in a multi-source NDB Cluster replication setup with three NDB Clusters having server IDs 1, 2, and 3. In this scenario, Cluster 1 replicates to Clusters 2 and 3; Cluster 2 also replicates to Cluster 3. This relationship is shown here: 4639