As long as the data is being accessed frequently, it is recalled from flash. When the data is no longer being accessed frequently, it is deleted from flash storage. Because the data was also written to tape, an archival copy of the data will still exist.
FLOUD, a similar approach to tiered storage, also uses flash for primary storage but cloud storage for secondary storage. Both approaches allow storage administrators to archive data as soon as it is written instead of having to move data into an archive at some later point in time.