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https://issues.apache.org/jira/browse/HDFS-9833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15284221#comment-15284221
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Kai Zheng commented on HDFS-9833:
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Thanks [~rakeshr] for the big work and I will take some look giving my feedback.
bq. How about optimizing the checksum recomputation logic to address multiple
datanode failures and reconstructing it together through another sub-task?
Sounds a good plan. Handling multiple block failures wouldn't impact big to the
existing codes that can work for single block failure. This is similar to the
ECWorker.
> Erasure coding: recomputing block checksum on the fly by reconstructing the
> missed/corrupt block data
> -----------------------------------------------------------------------------------------------------
>
> Key: HDFS-9833
> URL: https://issues.apache.org/jira/browse/HDFS-9833
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: Rakesh R
> Labels: hdfs-ec-3.0-must-do
> Attachments: HDFS-9833-00-draft.patch
>
>
> As discussed in HDFS-8430 and HDFS-9694, to compute striped file checksum
> even some of striped blocks are missed, we need to consider recomputing block
> checksum on the fly for the missed/corrupt blocks. To recompute the block
> checksum, the block data needs to be reconstructed by erasure decoding, and
> the main needed codes for the block reconstruction could be borrowed from
> HDFS-9719, the refactoring of the existing {{ErasureCodingWorker}}. In EC
> worker, reconstructed blocks need to be written out to target datanodes, but
> here in this case, the remote writing isn't necessary, as the reconstructed
> block data is only used to recompute the checksum.
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