We have a 2 node NW65SP4a cluster with iSCSI shared data on a third
server. The shared data server went down, and now the cluster nodes
will not re-join the cluster when booted.

If I type CLUSTER JOIN at a node command prompt, it says:

CLUSTER-<INFO>-<12033>: Joining
CLUSTER-<FATAL>-<12038>: SBD has reported a fatal error

I am pretty desperate to get this up again - how do I fix the SBD error?