Clarification on "cluster -> PXC-based slave". This happens when a node in the cluster has a traditional replication slave attached to it. That slave can be a Percona XtraDB Cluster instance but not being used as a cluster node, so wsrep_on=OFF.
Clarification on "cluster -> PXC-based slave". This happens when a node in the cluster has a traditional replication slave attached to it. That slave can be a Percona XtraDB Cluster instance but not being used as a cluster node, so wsrep_on=OFF.