FLASHC

The fundamental idea of MRv2 is to split up the two major functionalities of the JobTracker,
resource management
and job scheduling/monitoring, into separate daemons.

The idea is to have a
global ResourceManager (RM) and
per-application ApplicationMaster (AM).

An application is either a single job in the classical sense of Map-Reduce jobs or a DAG of jobs.

ambari-1.2.0-incubating-rc0 release candidate


http://incubator.apache.org/ambari/1.2.0/installing-hadoop-using-ambari/content/index.html


SVN source tag:
https://svn.apache.org/repos/asf/incubator/ambari/tags/release-1.2.0-rc0

Staging site:

在資料丟失達一定比例的時候，
namenode會進入safemode。

這時候可以採用

hadoop dfsadmin -safemode leave


or