Re: group replication with 2 data nodes and a witness?

[Frederic Descamps]

Hi Todd,

MySQL InnoDB Cluster (and so GR) is not like NDB. Nodes don't have a role as data node, etc..

They are data centric and therefor they all must have the same data.
To achieve at least one failure, you must have 3 members (to avoid split brain situation).

3 is always safer than 2 ;) and of course this is a very discussed topic for long time and not only in database. Mirroring was never the best HA solution at the end.

So I really NOT encourage you to use only 2 nodes. It's possible (everything is possible) to run it with something like an arbitrator. See https://github.com/mattlord/myarbitratord but I won't recommend it in production.

Cheers,