I encountered a strange problem with an installation of Percona XtraDB Cluster v. 5.7.
My configuration respect the standard installation guide, 3 nodes (all master) with one node started how bootstrap at cluster startup time; HAProxy is configured on the cluster with failover check, with “leastconn” configuration (how described here: https://www.percona.com/doc/percona-…s/haproxy.html).
My cluster work well but we have encountered a disaster scenario when, for some reason, node-1 (the bootstrapped) had network problems so HAProxy exclude it from the cluster and node-2 ed node-3 preserve all funcionality as expected. And here the problem: node-1 is returned online and, for reasons unknown to me, if a write occurred on Primary Component (node-2 & node-3), it create another cluster with the result that HAProxy, on the basis of “clustercheck” script, re-add node-1 to “global cluster” causing a Split-brain scenario with random writing on node-1 and node-2/node-3.
Is this a normal behavior? There is a problem in my configuration? If the connettivity problem happen on node-2 or node-3 the cluster it behaves as expected (node-2 go offline for some seconds, node-1 and node-3 keep active the cluster, write on cluster some data, reconnect node-2 than resync own data with donor node and finally node-2 is added to cluster ready to work).
Thanks so much.