How to set file permissions internally on hadoop

Hey guys, How can I configure HDFS so that internally I can set permissions on the data. I know there is a parameter called dfs.permissions that needs to be true, otherwise permissions won't work. Actually I had set it true previously, so that any user can use the HDFS data to run jobs on it. Now

Reducer NullPointerException

Hello everyone, I have 3 server(1 master, 2 slave) and I installed cdh3u2 on each server. I execute simple wordcount example but reducer had a NullPointerException. How can i solve this problem? The error log is that: Error: java.lang.NullPointerException at java.util.concurrent.ConcurrentH

Re: Problems with timeout when a Hadoop job generates a large number of key-value pairs

Hi Steve, I think I was able to reproduce your problem over the weekend (not sure though, it may be a different problem). In my case it was that the mappers were timing out during the merge phase. I also think the related tickets are MAPREDUCE-2177