Stop and start HA configuration

Check Galera cluster leader 

To stop or start the Galera cluster you should first identify the leader node.

1. On the datanodes, check the state of Galera:

   [root@datanodes2 /]# cd /var/lib/mysql/
   [root@datanodes2 mysql]# cat grastate.dat 
   # GALERA saved state
   version: 2.1
   uuid:    c0e2c5f4-e045-11e9-988e-d6d16254ad99
   seqno:   -1
   safe_to_bootstrap: 0

   If there is a node with safe_to_bootstrap=1, you should start the cluster on this node
   If no node is marked as safe_to_bootstrap, force it (using the virt IP).

Stop Galera cluster

To stop the Galera cluster do these steps.

1. Find the leader node as described above

2. Starting with the nodes that are not the leader. Stop the database on all nodes, .

   [root@datanodes2 /]# systemctl stop mariadb
   [root@datanodes1 /]# systemctl stop mariadb
   [root@datanodes0 /]# systemctl stop mariadb

Start Galera cluster

To start the Galera cluster, log in to the leader node.

1. Start the cluster with this command

   [root@datanodes0 /]# galera_new_cluster

2. On the other nodes, just start MariaDB or MySQL service

   [root@datanodes1 /]# systemctl start mariadb
   [root@datanodes2 /]# systemctl start mariadb

[root@datanodes1 mysql]# maxadmin show servers
[root@datanodes1 mysql]# maxadmin list servers

RabbitMQ Cluster check and rejoin

On each node do these commands.

rabbitmqctl stop_app
rabbitmqctl join_cluster rabbit@datanodes1
rabbitmqctl join_cluster rabbit@datanodes2
rabbitmqctl start_app
rabbitmqctl cluster_status