56f1136b_Hadoop_Troubleshooting__Possible_Problem
[Symptom] You get an error that you cluster is in "safe mode" [Possible Solution] First, wait a minute or two and then retry your command. If you just started your cluster, it's possible that it isn't fully initialized yet. If waiting a few minutes didn't help and you still get a "safe mode" error, check your logs to see if any of your data nodes didn't start correctly (either they have Java exceptions in their logs or they have messages stating that they are unable to contact some other node in your cluster). If this is the case you need to resolve the configuration issue (or possibly pick some new nodes) before you can continue. [Possible Problem] 
Your cluster enters safe mode when it hasn't been able to verify that all the data nodes necessary to replicate your data are up and responding. Check the documentation to learn more about safe mode.
Hadoop Troubleshooting
Possible Problem