Strange Behaviour in NDB after reconfiguration

[Felix Sidokhine]

Hello everyone,

Just wondering if anyone had such a case in practice. I had to reconfigure my network and the IP address of my NDB nodes had to be changed. In order to do this, I modified the config.ini file and changed the addresses. After that I restarted the cluster and ran the ndb_mgmd with the --initial option.

Overall everything worked as planned, but I do have a very strange output in the management console:

Cluster Configuration
---------------------
[ndbd(NDB)] 2 node(s)
id=2 @192.168.0.2 (mysql-5.7.18 ndb-7.6.3, Nodegroup: 0, *)
id=3 @192.168.0.3 (mysql-5.7.18 ndb-7.6.3, Nodegroup: 0, *)

[ndb_mgmd(MGM)] 1 node(s)
id=1 @192.168.0.1 (mysql-5.7.19 ndb-7.5.7)

[mysqld(API)] 3 node(s)
id=4 @192.168.0.2 (mysql-5.7.18 ndb-7.6.3)
id=5 @192.168.0.3 (mysql-5.7.18 ndb-7.6.3)
id=6 (not connected, accepting connect from 192.168.0.1)

Before the upgrade, only one of the nodes in the node group was marked with a star (as a master node), but suddenly I can see both nodes marked as masters, which is very strange. Has anyone ever encountered such a case and is there any action which needs to be taken in order to get the old behaviour back (where only a single node in the group was designated as master)?

The only solution I was able to find was to restart one of the nodes with the --initial option, but I'm a little reluctant to use this solution.

Any feedback would be greatly appreciated!