Oracle RAC Requirements

When you use Data Pump for backup and restore in packaging, the location of the directory object must be visible from all instances and all processes in the cluster. The object is named DATICAL_DATAPUMP_DIR by default, but you can use a different name.  

A typical implementation uses a shared file system or drive for the location of the directory. 

Take care that all instances access the same physical directory.  That directory must be the single point for backup and restore operations.