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https://issues.apache.org/jira/browse/HDFS-9205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15435895#comment-15435895
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Ravi Prakash commented on HDFS-9205:
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Thanks for the change Nicholas! Should this line be modified?
https://github.com/apache/hadoop/blob/a1f3293762dddb0ca953d1145f5b53d9086b25b8/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/LowRedundancyBlocks.java#L62
.
I think most often this queue had missing blocks, so it didn't really make
sense to re-replicate missing blocks anyway. We should be careful about
removing this queue though, because its where the [count of missing blocks is
taken
from|https://github.com/apache/hadoop/blob/a1f3293762dddb0ca953d1145f5b53d9086b25b8/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java#L4112]
> Do not schedule corrupt blocks for replication
> ----------------------------------------------
>
> Key: HDFS-9205
> URL: https://issues.apache.org/jira/browse/HDFS-9205
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Tsz Wo Nicholas Sze
> Priority: Minor
> Fix For: 2.8.0
>
> Attachments: h9205_20151007.patch, h9205_20151007b.patch,
> h9205_20151008.patch, h9205_20151009.patch, h9205_20151009b.patch,
> h9205_20151013.patch, h9205_20151015.patch
>
>
> Corrupted blocks by definition are blocks cannot be read. As a consequence,
> they cannot be replicated. In UnderReplicatedBlocks, there is a queue for
> QUEUE_WITH_CORRUPT_BLOCKS and chooseUnderReplicatedBlocks may choose blocks
> from it. It seems that scheduling corrupted block for replication is wasting
> resource and potentially slow down replication for the higher priority blocks.
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