In some scenarios, the newly inserted data may be evicted to LAS without writing any disk image for that key. From the LAS records, it is not possible to know that there is a disk image exists for this key with a value. So once the oldest_timstamp moves beyond the timestamp of the record inserted, the LAS sweep server cleans the record as it is an obsolete record. Later if the page gets instantiated, the new key gets missed and thus the data loss can happen.