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From Rob Hamilton <...@lotame.com>
Subject RE: Decommissioning Nodes
Date Thu, 22 Jan 2009 17:26:48 GMT
I wasn't able to get decommissioning to work at all and found that just taking the node down
got it out of the cluster. What version are you running and how are you initiating the decommissioning?


Rob Hamilton - VP Network Operations 
P +1 (410) 379-2195 x 240   
E rob@lotame.com   
6085 Marshalee Drive, Suite 210   
Elkridge, MD 21075   

-----Original Message-----
From: Hargraves, Alyssa [mailto:alyssa@WPI.EDU] 
Sent: Wednesday, January 21, 2009 7:35 PM
To: core-user@hadoop.apache.org
Subject: Decommissioning Nodes

Hello Hadoop Users,

I was hoping someone would be able to answer a question about node decommissioning.  I have
a test Hadoop cluster set up which only consists of my computer and a master node.  I am looking
at the removal and addition of nodes.  Adding a node is nearly instant (only about 5 seconds),
but removing a node by decommissioning it takes a while, and I don't understand why. Currently,
the systems are running no map/reduce tasks and storing no data. DFS Health reports:

7 files and directories, 0 blocks = 7 total. Heap Size is 6.68 MB / 992.31 MB (0%)
Capacity	:	298.02 GB
DFS Remaining	:	245.79 GB
DFS Used	:	4 KB
DFS Used%	:	0 %
Live Nodes 	:	2
Dead Nodes 	:	0

Node 	 Last Contact 	 Admin State 	 Size (GB) 	 Used (%) 	 Used (%) 	 Remaining (GB) 	 Blocks
master	0	In Service	149.01	0	
	122.22	0
slave	82	Decommission In Progress	149.01	0	
	123.58	0 

However, even with nothing stored and nothing running, the decommission process takes 3 to
5 minutes, and I'm not quite sure why. There isn't any data to move anywhere, and there aren't
any jobs to worry about.  I am using 0.18.2.

Thank you for any help in solving this,
Alyssa Hargraves

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