Portion of data stream or data block 200 is to be stored in storage device 210, representing {TAIL ~ a storage device} of {HEAD ~ a storage system}  
Portion of data stream or data block 200 is to be stored in storage device 210 , representing { TAIL ~ a storage device } of { HEAD ~ a storage system }
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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH