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https://issues.apache.org/jira/browse/HDFS-14699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16920846#comment-16920846
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Zhao Yi Ming commented on HDFS-14699:
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[~ayushtkn] For The UT part, because I added the new test case
testChooseSrcDatanodesWithDupEC which is used to test my fix. If you do not
apply the patch, the new test case is not added, so the UT passed.
Good point for the block index, I agree we do NOT need to recalculate the block
index, I will try to fix this in next patch. But we can NOT put the
liveBlockIndices.add(blockIndex) before following block, the reason is the EC
reconstruction work will not be controlled by the replicationStreamsHardLimit
configuration, if we move liveBlockIndices.add(blockIndex) before following
block. In this way it will introduce the DN high resource usage (CPU and
Memory).
if (node.getNumberOfBlocksToBeReplicated() >=
replicationStreamsHardLimit) \{
continue;
}
> Erasure Coding: Can NOT trigger the reconstruction when have the dup internal
> blocks and missing one internal block
> -------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-14699
> URL: https://issues.apache.org/jira/browse/HDFS-14699
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: ec
> Affects Versions: 3.2.0, 3.1.1, 3.3.0
> Reporter: Zhao Yi Ming
> Assignee: Zhao Yi Ming
> Priority: Critical
> Labels: patch
> Attachments: HDFS-14699.00.patch, HDFS-14699.01.patch,
> HDFS-14699.02.patch, HDFS-14699.03.patch, HDFS-14699.04.patch,
> image-2019-08-20-19-58-51-872.png, image-2019-09-02-17-51-46-742.png
>
>
> We are tried the EC function on 80 node cluster with hadoop 3.1.1, we hit the
> same scenario as you said https://issues.apache.org/jira/browse/HDFS-8881.
> Following are our testing steps, hope it can helpful.(following DNs have the
> testing internal blocks)
> # we customized a new 10-2-1024k policy and use it on a path, now we have 12
> internal block(12 live block)
> # decommission one DN, after the decommission complete. now we have 13
> internal block(12 live block and 1 decommission block)
> # then shutdown one DN which did not have the same block id as 1
> decommission block, now we have 12 internal block(11 live block and 1
> decommission block)
> # after wait for about 600s (before the heart beat come) commission the
> decommissioned DN again, now we have 12 internal block(11 live block and 1
> duplicate block)
> # Then the EC is not reconstruct the missed block
> We think this is a critical issue for using the EC function in a production
> env. Could you help? Thanks a lot!
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