Petas3,
*On URE another node will serve eventually it - this is happening on StarWind fabric level or client level?
This is happening on StarWind level.
There will no notice of this error on the connected client except perhaps a longer delay?
You can it in StarWind Management Console, StarWind logs and Windows Application logs.
*The resync process will begin automatically? - resulting in a full resync and node automatic restoration after some time?
Yes.
In a 3 node cluster reads for this resync process are striped to other 2 nodes, or just 1 node is used?
The resync process will start from all the nodes that are synchronized, in this case from 2 nodes.
*Can you perhaps somehow force a partial sync - on a multiple TB volume this could have significant benefits? Or is it best-practice to have a LUN with multiple smaller (1-2TB) HA volumes over a drive/RAID?
Yes, you can change the priority of the synchronization process. You can create multiple smaller HA volumes over a drive/RAID. It depends on the type of the underlying storage and type of VM you plan to run on these HA volumes.