{HEAD ~ The data transaction system} uses a first stage for transferring the data unit from the upper layer to the storage layer, and {TAIL ~ a second stage} to save the transferred data unit independent of the upper layer 
uses
{ HEAD ~ The data transaction system } uses a first stage for transferring the data unit from the upper layer to the storage layer , and { TAIL ~ a second stage } to save the transferred data unit independent of the upper layer
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH