Since on write operations , no actual data are needed back , there are two approaches for situations of write-misses : Both write-through and write-back policies can use either of these write-miss policies , but usually they are paired in this way : Entities other than the cache may change the data in the backing store , in which case the copy in the cache may become out-of-date or stale .
If the data changed in the backing store , the copy in the cache will be out of date , or stale .