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From Harold Lim <rold...@yahoo.com>
Subject Re: Question about HDFS Architecture
Date Fri, 21 Aug 2009 13:42:19 GMT
> 
> Also, if a file has multiple replicas stored on multiple
> datanodes on the same "rack", how does the
> namenode pick which datanode the client has to talk to? In
> this case, all datanodes are homogeneous, which makes the
> "rack-awareness" unimportant to the decision
> making.
> 
> 
> I believe the datanode itself picks. In the absence of rack
> information, it's choice is random (unless one is
> localhost, in which case that one gets used). 
> 

Hi Aaron,

Did you mean the client itself picks? So the namenode simply gives the list of datanode that
has the file, and the client picks from this list?



Thanks,
Harold



      

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