This categorization can be based on dividing the requests between write and read requests, or between requests that alter data stored on the storage device and requests that do not alter {HEAD ~ data} on {TAIL ~ the storage device} 
on
This categorization can be based on dividing the requests between write and read requests , or between requests that alter data stored on the storage device and requests that do not alter { HEAD ~ data } on { TAIL ~ the storage device }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL