Are you seeking something simple rather than sophisticated? If so, you can
use the controller local disk for StateSaveLocation and place a cron job
(on the same node or somewhere else) to take that data out via e.g. rsync
and put it where you need it (NFS?) for the backup control node to use
You can try DRBD
https://linbit.com/drbd/
or a shared-disk (clustered) FS like GFS2, OCFS2, etc
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html-single/configuring_gfs2_file_systems/index
