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https://issues.apache.org/jira/browse/HDFS-9657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15145342#comment-15145342
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Zhe Zhang commented on HDFS-9657:
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This is an interesting idea. However, when some internal blocks of a group are
missing, the entire block group is *at risk*. Should we really wait until a
certain wall clock time to start reconstruction? Looks like throttling is a
better idea and I believe we are already throttling the amount of DN work in a
given time window.
> Schedule EC tasks at proper time to reduce the impact of recovery traffic
> -------------------------------------------------------------------------
>
> Key: HDFS-9657
> URL: https://issues.apache.org/jira/browse/HDFS-9657
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Li Bo
> Assignee: Li Bo
> Attachments: HDFS-9657-001.patch, HDFS-9657-002.patch
>
>
> The EC recover tasks consume a lot of network bandwidth and disk I/O.
> Recovering a corrupt block requires transferring 6 blocks , hence creating a
> 6X overhead in network bandwidth and disk I/O. When a datanode fails , the
> recovery of the whole blocks on this datanode may use up the network
> bandwith. We need to start a recovery task at a proper time in order to give
> less impact to the system.
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