A method of a buffer memory device, a storage system, and a buffer memory device are provided. The method of the buffer memory device, the buffer memory device having a lower tier memory and a higher tier memory, may include receiving a new entry request, determining that the new entry request includes an HOL entry, selecting an entry on the higher tier memory to be tiered down to the lower tier memory in response to determining that the new entry request includes an HOL entry, removing the selected entry from the higher tier memory, storing the HOL entry in the higher tier memory of the buffer memory device, and outputting the HOL entry to an arbiter.