A method begins by a processing module of a dispersed storage network (DSN) detecting a likelihood of having a missing encoded data slice based on local physical to DSN address mapping information. When the likelihood of having the missing encoded data slice exists, the method continues with the processing module sending a query regarding the missing encoded data slice to another storage unit of the DSN and receiving a response to the query from the other storage unit. When the response includes identity of a related encoded data slice of a set of encoded data slices, the method continues with the processing module commencing execution of a rebuilding function to generate a new encoded data slice to replace the missing encoded data slice.