our current scenario is the following:
- 5 nodes PXC
- DC1 (AWS): 3 nodes spanned on 3 different AZ
- DC2 (on-prem): 2 nodes
DC2 is going to be decomissioned in order to deploy the new one DC3 in a different location, with different hardware and different subnets.
DC3 will come up after DC2 complete decomissioning, so I need to reduce PXC Cluster removing DC2 nodes and then put 2 DC3 nodes into the cluster sequentially.
What’s the best practices to do that with less downtime possible? Do I need to completely shutdown the cluster in order ro reduce it?
I think I could answer to my own question after some studying and test sessions: the cluster does not need to completely shutdown and nodes can be removed and added as soon as quorum is kept on DC1 and mysql is graceful shutdowned on decomissioned nodes.
The only document I found where the safely nodes removal is clearly documented is the MariaDB cookbook: