Questions about Hadoop logs and mapred.local.dir

[sam liu]

Hi Experts,

1. The size of mapred.local.dir is big(30 GB), how many methods could clean
it correctly?
2. For logs of NameNode/DataNode/JobTracker/TaskTracker, are they all
rolling type log? What's their max size? I can not find the specific
settings for them in log4j.properties.
3. I find the size of dfs.name.dir and dfs.data.dir is very big now, are
there any files under them could be removed actually? Or all files under
the two folders could not be removed at all?

Thanks!