A partially relocated object identifier store including "copy from" and "copy to" identifier storage accessible to write and read barrier logic allows the write and read barrier logic to selectively direct store- and load-oriented accesses to an appropriate FromSpace or ToSpace instance of a partially relocated memory object, in accordance with the memory object's partial relocation state. In some embodiments, the barriers trap to a partially relocated object trap handler. In other embodiments, the write barrier itself directs accesses without software trap handler overheads. Optional "how far" indication storage facilitates differentiation by the barrier logic, or by the partially relocated object trap handler, between a copied portion and an uncopied portion of the partially relocated memory object.