I am trying to add a node to an existing cluster:

existing: 2 nodes OES 2015 SP1, old Blades
new: ESXi 6.5 VMs, OES 2018, volumes mapped as RDM disks

Disks are visible on the new server, nssmu shows correct NSS pools, sbdutil
-f finds the SBD partition.

But when I start NCS the server immediately crashes; this results in a
reboot-loop until I unmap the SBD volume from the VM.

My goal is to move the cluster resources to 2 new nodes and then remove the
old ones. Do I miss something? Why does the node crash as soon as it sees
the SBD partition?