Namenode High Availability

Last week I tried Namenode HA using Cloudera Distribution of Hadoop (CDH 4.5.0).

It is very easy to configure and automatic fail over is happening smoothly. Tried the redundancy by pulling the power cable of one of the namenodes. It was successful. For more details, visit the official website of Cloudera.
http://www.cloudera.com/content/cloudera-content/cloudera-docs/CDH4/latest/CDH4-Installation-Guide/CDH4-Installation-Guide.html

I have tried this HA in a 64 TB hadoop cluster.