How do I correctly remove nodes in Hadoop?

Question

I\'m running Hadoop 1.1.2 on a cluster with 10+ machines. I would like to nicely scale up and down, both for HDFS and MapReduce. By \"nicely\", I mean that I require that da

Answer 1

While decommissioning in progress, temporary or staging files get cleaned automatically. These files are missing now and hadoop is not recognizing how that went missing. So the decommissioning process keeps waiting until that is resolved even though the actual decommissioning is done for all the other files.

In Hadoop GUI - if you notice the parameter "Number of Under-Replicated Blocks" is not reducing over the time or almost constant then this is the reason likely.

So list the files using below command

hadoop fsck / -files -blocks -racks

If you see those files are temporary and not required then delete those files or folder

Example: hadoop fs -rmr /var/local/hadoop/hadoop/.staging/* (give the correct path here)

This would solve the problem immediately. De-commissioned nodes will move to Dead Nodes in 5 mins.