Sybase recommends that you configure each instance on a different node ie. one node for each instance. However, for a testing environment, you can create a simulated cluster on a single node with all instances running on that node. For best performance make sure the number of engines in all instances running on a single node does not exceed the number of CPUs on that node.
Additionally, Sybase strongly recommends tuning the runnable process search count parameter to '3' in such an environment. This can be set using the sp_configure stored procedure.
