title: What additional benefit does Yarn bring to the existing map reduce?
body: <p>Yarn differs in its infrastructure layer from the original map reduce architecture in the following way: </p>
  
  <p>In YARN, the job tracker is split into two different daemons called <code>Resource Manager</code> and <code>Node Manager</code> (node specific). The resource manager only manages the allocation of resources to the different jobs apart from comprising a scheduler which just takes care of the scheduling jobs without worrying about any monitoring or status updates. Different resources such as memory, cpu time, network bandwidth etc. are put into one unit called the <code>Resource Container</code>. There are different <code>AppMasters</code> running on different nodes which talk to a number of these resource containers and accordingly update the Node Manager with the monitoring/status details.</p>
  
  <p>I want to know that how does using this kind of an approach increase the performance from the map-reduce perspective? Also, if there is any definitive content on the motivation behind Yarn and its benefits over the existing implementation of Map-reduce, please point me to the same.</p>