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From "Zhu Huijun" <nautilu...@gmail.com>
Subject Re: Specifying the positions of replicas
Date Tue, 26 Feb 2008 14:29:13 GMT
Yes. I stop DFS, compile the sources, then start DFS and copy some files to
see.

2008/2/25, Lohit Vijaya Renu <lohit@yahoo-inc.com>:
>
>
> This has to be invoked. After making the changes did you restart DFS using
> the new changes?
> Thanks,
> Lohit
>
> -----Original Message-----
> From: Zhu Huijun [mailto:nautilushj@gmail.com]
> Sent: Mon 2/25/2008 2:31 PM
> To: core-dev@hadoop.apache.org
> Subject: Specifying the positions of replicas
>
> Hi, all,
>
> Currently our group want to try some new data layout schemes on Hadoop,
> but
> I encounter some problems.
>
> In Hadoop, each block has 3 replicas by default. It is said in the
> documents
> that two of them are put randomly in the same rack, and the third is put
> at
> another rack. This procedure is also clear in the source code of the class
> org.apache.hadoop.dfs.ReplicationTargetChooser.
>
> What I did was adding a simple System.out.println("function name") clause
> in
> each function in ReplicationTargetChooser, and intended to check which
> ones
> are called to select the target nodes for replicas. However, when I use
> "./bin/hadoop dfs -copyFromLocal" command to copy some files from the
> local
> file system to HDFS, it seems none of the functions in the
> ReplicationTargetChooser is called, because nothing is printed out on the
> screen or the log files.
>
> I preciate if someone can tell me where I can modify to control the target
> nodes of replicas. Thank you!
>
> Have a nice day!
>
> Huijun Zhu
>
>

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