One day, I just created a fresh centos and download/install the hadoop, by default it runs on local mode. so I just change the config to run in distributed mode. When I run bin/start-all.sh. get the follow errors in the tasktrackr log.
2011-08-16 21:00:12,136 INFO org.apache.hadoop.mapred.JobTracker: STARTUP_MSG:
It looks like perfect, right, cause I just copied the setting from the default xml, while, I just keep the weird error.
well, here is final xml that works great, I highlighted the difference, I forgot to put the property tag. so the runtime will ignore this xml and pick up the default settings.
Summary, when you get weird error, check the log first, then make sure those conf xml are in right format that comforts the scheme