Hi #rke2! I want to create a high-availability RKE2 cluster where it is necessary to distribute nodes at two sites (e.g. EU-A and EU-B geographically distributed sites). It is recommended to have an odd number of masters in a cluster. But it is necessary for each sites to be failure tolerance. Is it good idea when I place 3 master nodes each sites (EU-A 3 master nodes, EU-B 3 master nodes)? Then fault tolerance is ensured both within and between sites. Am I wrong? I don't want to build multi-cluster RKE2 architecture because of Longhorn.

You need a majority (MORE than half, not exactly half) of etcd available, so an even number is always bad. The 6th node is an extra piece of hardware that can fail but provides no extra failure tolerance. What you described will fail if EITHER location is unavailable, because NEITHER one has a quorum on their own. What you want isn't possible with 2 locations. You need 3 locations to be able to lose any 1. With 2 the best you can do is have a majority in one of the locations so that it still works if the other is unavailable (but not vice versa).

thanks @full-painter-23916, sadly we don't have 3 locations.

A third one could be one vm in AWS or something...