1. First, follow the instructions [here](https://github.com/mesos/mesos/wiki/Running-Mesos-On-Mac-OS-X-Snow-Leopard-(Single-Node-Cluster)) to get a single instance of Hadoop running.

2. Next, we'll get a second instance of the same version of Hadoop that ships with Mesos running:

   • Make another copy of Hadoop:
     ~/mesos$ cp -R frameworks/hadoop-0.20.2 ~/hadoop
   • Modify necessary ports:
     • In conf/mapred-site.xml.template, change the mapred.job.tracker port from 9001 to 9002.
     • In src/mapred/mapred-default.xml, change the mapred.task.tracker.http.address port and the
       mapred.job.tracker.http.address port both to 0.
   • Build Hadoop:
     ~/hadoop$ ant
~/hadoop$ ant compile-core jar
~/hadoop$ ant examples jar
   • Start up Mesos:
     ~/mesos$ bin/mesos-master
~/mesos$ bin/mesos-slave --master=mesos://master@localhost:5050
   • Start up HDFS (we'll have one instance of HDFS that both instances of Hadoop access):
     ~/mesos/frameworks/hadoop-0.20.2$ bin/hadoop namenode
~/mesos/frameworks/hadoop-0.20.2$ bin/hadoop datanode
   • Start the jobtrackers:
     ~/mesos/frameworks/hadoop-0.20.2$ bin/hadoop jobtracker
~/hadoop$ bin/hadoop jobtracker
   • Run some tests:
     ~/mesos/frameworks/hadoop-0.20.2$ bin/hadoop jar build/hadoop-0.20.3-dev-examples.jar wordcount ~/gutenburg/ ~/output
~/hadoop$ bin/hadoop jar build/hadoop-0.20.3-dev-examples.jar wordcount ~/gutenburg/ ~/output1
   • At this point, you should be able to run both instances of wordcount at the same time.