A method begins by tracking age related failure levels of memory devices within the storage unit. The method continues by maintaining a data location table that maps a range of DSN addresses allocated to the storage unit to the memory devices and further records storing of encoded data slices having specific DSN addresses within the memory devices. The method continues, when the age related failure level for a memory device compares unfavorably to a first failure level threshold, by determining to reassign a portion of DSN addresses assigned to the memory device. The method continues by identifying a second memory device having a corresponding age related soft failure level comparing favorable to the first failure level threshold. The method continues by reassigning the portion of the DSN addresses from the memory device to the second memory device and updating the data location table.