ODBC Connection As Clustered Resource
The linked server "lives" in the clustered SQL Server instance, so whichever node the SQL Server happens to be running on, the linked server should run fine....as long as you've installed the required ODBC/OLEDB driver(s) on each node.

Looking at that error, I'm assuming the linked server doesn't work at all on any node. I suspect you'd have the same problem on a standalone SQL Server too - it seems to me to be a driver issue. Whose OLEDB driver are you using?

I'm sure you've read the following IBM KB:
http://www-01.ibm.com/support/docview.wss?uid=swg21195578