Re: How to replace the storage on a datanode without formatting the namenode?

[Alexandra Alecu <al...@gmail.com>]

jason hadoop wrote:
> 
> You can decommission the datanode, and then un-decommission it.
> 

Thanks Jason, I went off and figured out what to decomission a datanode
means and this looks like a very neat idea.

 Decommissioning requires that the nodes be listed in the dfs.hosts.excludes
file. The administrator runs the "dfsadmin -refreshNodes" command. 

I will need some reconfiguring to be able to do this as the local storage
has exactly the same path on all my datanodes. Essentially, if I change
dfs.data.dir taking away the path to the local storage, it will take it away
on all the datanodes. Therefore I wonder if this advice uncovers a problem
with my cluster configuration. 

When i first installed hadoop on the cluster, since most settings looked the
same for all nodes, I thought  to set same location paths for the local
storage and this way making it easier to put the configuration files in one
directory and then create symlinks from all the hadoop home folders to this
one configuration directory.

Is this what usually people do or have I gone in a completely wrong
direction?
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