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https://issues.apache.org/jira/browse/HDFS-782?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13500914#comment-13500914
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Putu Yuwono commented on HDFS-782:
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I have several question for you guys who are more expert than me
1.What should be considered during the dynamic replicating process (ex:Block
Usage, Cluster Size)? How many new replicas should be created?
2.How to communicate between data nodes without bothering the name node?
3.How to find the best candidate for placing a new replica? What should be
considered for choosing the data node?
4.How to decide which one is better, moving or replicating? Is it depends on
the usage pattern?
> dynamic replication
> -------------------
>
> Key: HDFS-782
> URL: https://issues.apache.org/jira/browse/HDFS-782
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Ning Zhang
>
> In a large and busy cluster, a block can be requested by many clients at the
> same time. HDFS-767 tries to solve the failing case when the # of retries
> exceeds the maximum # of retries. However, that patch doesn't solve the
> performance issue since all failing clients have to wait a certain period
> before retry, and the # of retries could be high.
> One solution to solve the performance issue is to increase the # of replicas
> for this "hot" block dynamically when it is requested many times at a short
> period. The name node need to be aware such situation and only clean up extra
> replicas when they are not accessed recently.
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