Adding node 4 to XtraDB MySQL cluster and using Master-Slave on Node5.

[jbiancot]

Hi there,

We have a Percona XtraDB MySQL cluster with 3 nodes, and we have ProxySQL set load-balancer mode.

On the 3 nodes, we are forcing synchronization using wsrep_sync_wait=7

We want to add a new node to the cluster, I will call it Node 4, it is easy to add it to the current 3 node Percona XtraXB “MySQL” cluster but I don’t want Node 4 to serve any traffic, then we are modifying the shell script “Scheduler” which the ProxySQL uses to check the nodes, ProxySQL will be ignoring the IP of the Node 4, that way ProxySQL is unaware of the existence of Node 4, and traffic will not be sent to it.

Node 4 in in the same datacenter than Node1-3 but it is in another VLAN, then there is a bit of delay/lag, because of that I am thinking in not having the flag “wsrep_sync_wait=7” for Node 4.

Node 4 beside being part of the cluster, I would like to setup as a “master” enabling the log-bin, traditional MySQL configuration (Master - Slave)

On another data center, not that far from where is our Nodes 1-4, I want to have a new node running Percona MySQL single instance “Node 5”, and it would be configure as a slave, pointing to its master Node 4.

Any advice or suggestions?

Thanks in advance.

[jbiancot]

We were able to add the Node 4 to the Percona XtraDB MySQL Cluster. The node 1-3 are setup using wsrep_sync_wait=7, on Node 4 we didn’t setup that flag, then the nodes 1-3 get propagated and force to be sync 100%, the node 4 could be delayed for a few milliseconds but it is all-right.

On the ProxySQL we changed the scheduler script to ignore node 4, it only sends request/queries to node 1-3. The node 4 acts as a master on a traditional MySQL master-slave way beside be part of the XtraDB cluster. Node 5 which is in another data-center is acting as slave pointing to node 4. So far so good !

I think I will write a basic Java SpringBoot v2 application to check for Node 5 and if it gets out of sync, send us an e-mail.

Thanks.