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