② Notes No reduce can begin until map is complete Master must communicate locations of ntermediate files Tasks scheduled based on location of data If map worker fails any time before reduce finishes, task must be completely rerun MapReduce library does most of the hard work for usNotes 39 • No reduce can begin until map is complete • Master must communicate locations of intermediate files • Tasks scheduled based on location of data • If map worker fails any time before reduce finishes, task must be completely rerun • MapReduce library does most of the hard work for us!