CDH4 Hadoop Ubuntu precise server

I got this error "JAVA_HOME "
When trying to install CDH4 of Cloudera Hadoop standalone version.
Although i did all the needed configuration + echo $JAVA_HOME is fine.
+ writing "java" works + writing "java -version" works ok .
Nothing really helped except
1. go to /etc/hadoop/conf
2. edit hadoop-env.sh
add export JAVA_HOME=/usr/lib/jvm/jdk1.6.0_32
then try again, i was trying to format the namenode.

Hoped it helped.
Dor

YARN vs MRV2

YARN is the up coming version 2.0.0 which is now in alpha and MRV2 as for map reduce version 2.0
They used to call mrv2 for the previous 0.23 version.

More about it can be found in cloudera site.