{HEAD ~ The data} are migrated into {TAIL ~ RAID 5 configurations} as a background operation, to minimize the disk space lost 
are migrated into
{ HEAD ~ The data } are migrated into { TAIL ~ RAID 5 configurations } as a background operation , to minimize the disk space lost
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH