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Date: Tue, 20 Nov 2012 06:34:06 +0000 (UTC)
From: "Putu Yuwono (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <1289037982.5411.1353393246945.JavaMail.jiratomcat@arcas>
Subject: [jira] [Commented] (HDFS-782) dynamic replication
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    [ https://issues.apache.org/jira/browse/HDFS-782?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13500862#comment-13500862 ] 

Putu Yuwono commented on HDFS-782:
----------------------------------

Is there anybody who's been working on this issue?
It's been 3 years but still unresolved.

                
> 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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