Can mariadb-galera cluster be configured without data replication but simply in failover mode? I envision such configuration as one active master server and one backup server, both using the same mounted ScaleIO volume ( already with built-in data redundancy)...Is such scenario possible? Thank you,
No. Galera doesn't work with shared storage, as far as I know.
The way initial cluster members join is by basically blowing away the MySQL datadir, and rsyncing it over from another peer. That would not work out well with shared storage.
Plus, I don't think MySQL itself is really built for shared storage...