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Posted to hdfs-issues@hadoop.apache.org by "Uma Maheswara Rao G (Commented) (JIRA)" <ji...@apache.org> on 2012/03/07 08:07:58 UTC

[jira] [Commented] (HDFS-1765) Block Replication should respect under-replication block priority

    [ https://issues.apache.org/jira/browse/HDFS-1765?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13224058#comment-13224058 ] 

Uma Maheswara Rao G commented on HDFS-1765:
-------------------------------------------

Thanks a lot Suresh, for merging it to 23 branch. I will mark this issue as resolved now, as it was left for 0.23 version merge.
                
> Block Replication should respect under-replication block priority
> -----------------------------------------------------------------
>
>                 Key: HDFS-1765
>                 URL: https://issues.apache.org/jira/browse/HDFS-1765
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.23.0
>            Reporter: Hairong Kuang
>            Assignee: Uma Maheswara Rao G
>             Fix For: 0.24.0, 0.23.3
>
>         Attachments: HDFS-1765.patch, HDFS-1765.patch, HDFS-1765.patch, HDFS-1765.patch, HDFS-1765.pdf, underReplicatedQueue.pdf
>
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> Currently under-replicated blocks are assigned different priorities depending on how many replicas a block has. However the replication monitor works on blocks in a round-robin fashion. So the newly added high priority blocks won't get replicated until all low-priority blocks are done. One example is that on decommissioning datanode WebUI we often observe that "blocks with only decommissioning replicas" do not get scheduled to replicate before other blocks, so risking data availability if the node is shutdown for repair before decommission completes.

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