Because of the way we setup the scripts to automatically install DB2 on Linux Service Nodes, if the db2install script is not run then the cfgloc file will not exist on the SN. Updatenode only runs servicenode, xcatserver,xcatclient. xcatserver moves the cfgloc file on the SN and then it is put back by db2install. This was so we could run the db2sqlsetup script to setup DB2 automatically.
To fix need to add, for DB2 also to run db2install on updatenode -k to SN.