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https://issues.apache.org/jira/browse/HDFS-6682?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14647666#comment-14647666
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Yi Liu commented on HDFS-6682:
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{quote}
There's a big advantage to having this metric: it's extremely useful to know
how backlogged the replication queue is as a determinant of namenode health on
extremely large clusters.
{quote}
We have many ways to know about namenode health or in heavy load.
It's not worth.
Thanks Akira for reverting.
> Add a metric to expose the timestamp of the oldest under-replicated block
> -------------------------------------------------------------------------
>
> Key: HDFS-6682
> URL: https://issues.apache.org/jira/browse/HDFS-6682
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Akira AJISAKA
> Assignee: Akira AJISAKA
> Labels: metrics
> Attachments: HDFS-6682.002.patch, HDFS-6682.003.patch,
> HDFS-6682.004.patch, HDFS-6682.005.patch, HDFS-6682.006.patch, HDFS-6682.patch
>
>
> In the following case, the data in the HDFS is lost and a client needs to put
> the same file again.
> # A Client puts a file to HDFS
> # A DataNode crashes before replicating a block of the file to other DataNodes
> I propose a metric to expose the timestamp of the oldest
> under-replicated/corrupt block. That way client can know what file to retain
> for the re-try.
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