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
