This read-only SnmpAdminString indicates the age of the oldest data present in the DRE cache, formatted as <x>d<x>h<x>m, and the description gives the example of a full 1GB cache where new writes evict the oldest data in FIFO order, so this object reports how old that oldest surviving data currently is. An admin uses this to judge the effective cache retention window, since a shorter age here under steady load implies faster cache turnover and potentially less deduplication benefit for infrequently repeated data. If this age suddenly drops much lower than usual, an admin would suspect a burst of new, unique data has rapidly evicted older cached content.