how openstack swift select the hand off node when a primary node is not available? and how to find out all the objects sent to hand off node during the unavailable period? thanks!

a simple case is 

proxy send create object A request to node X,  X is down. request send to hand off node Y, store A in Y there are N such objects in Y now X is up proxy try to read object A, now both X and Y are up

simple way is to contact both X and Y and find out which one owns A. but this need double look up. anyway to save one look up?

and also how to know all the N objects and handover back to X?

thanks.