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HDFS, mail # user - a question about controlling roles (read, write) of data node


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Kyungyong Lee 2012-05-20, 19:07
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Re: a question about controlling roles (read, write) of data node
Harsh J 2012-05-21, 02:53
Kyungyong Lee,

One way: This may be possible to do if you inflate the
"dfs.datanode.du.reserved" property on the specific DataNode to a very
large bytes value (> maximum volume size). This way your NN will still
consider the DN as a valid one that carries readable blocks, but when
writing files this DN will never be selected due to its
false-lack-of-space report.

On Mon, May 21, 2012 at 12:37 AM, Kyungyong Lee <[EMAIL PROTECTED]> wrote:
> Hello,
>
> I would like to ask if I can do the following. Assuming that I have a
> datanode, i.e., dn1, which already contains some useful blocks. Here,
> I do not want to save new data blocks to the datanode, but I still
> want to use the blocks that already exist in the datanode (dn1).
> I considered to use exclude file (dfs.hosts.exclude). However, if I
> add "dn1" to the exclude file list, I cannot use blocks that are
> already contained in dn1. If it is right, can you please give me some
> guidances to do what I'm thinking using HDFS?
>
> Thanks,

--
Harsh J
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Kyungyong Lee 2012-05-21, 14:03