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HDFS >> mail # user >> Question about HDFS Architecture


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Re: Question about HDFS Architecture
>
> 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
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB