We are using Galera clustering with MariaDB on 3 nodes for that. We are using it since 2014. First in line is a HAProxy which directs the traffic to one of the

We are using Galera clustering with MariaDB on 3 nodes for that. We are using it since 2014. First in line is a HAProxy which directs the traffic to one of the 3 nodes. If one of the nodes goes down HAProxy directs the traffic to the other two nodes. This works quite well, as long as not all 3 nodes are down / lose network connection. After that you have to initialise the cluster again. One node is the new master and all later changes in the other databases are overwritten. Then we connect each node to the new cluster. The biggest problems are write intense operations. We had more luck using two nodes as read nodes and using the third node as write node. When the data in two nodes got updated simultaneously the performance suffered heavily. After some smarter scheduling it works pretty well (as long as not all the nodes go down or the network connection between the nodes is lost). The slowest node can block the write operations for all the other nodes.