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https://issues.apache.org/jira/browse/HDFS-11285?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15806306#comment-15806306
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Andrew Wang commented on HDFS-11285:
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Thanks for the diagram, that's something we should put as a code comment in
DecommissionManager :)
Like you say, it looks like we don't have a 5->6 transition.
BlockManager#isNodeHealthyForDecommissionOrMaintenance requires the node to be
alive, and actually will log a WARN with the procedure you've been running with
5->4->6. So at least it seems like this behavior is intentional.
I'm betting though that the straggler blocks on the DN are caused by
open-for-write files though, and I'd prefer to solve that problem rather than
adding a 5->6 transition. Could you run {{hdfs fsck}} with {{-openforwrite}}
and {{-files -blocks -locations}} to confirm? Also check in the NN logs since
we should be printing information about what blocks are preventing
decommissioning.
> Dead DataNodes keep a long time in (Dead, DECOMMISSION_INPROGRESS), and never
> transition to (Dead, DECOMMISSIONED)
> ------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-11285
> URL: https://issues.apache.org/jira/browse/HDFS-11285
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.7.1
> Reporter: Lantao Jin
> Attachments: DecomStatus.png
>
>
> We have seen the use case of decommissioning DataNodes that are already dead
> or unresponsive, and not expected to rejoin the cluster. In a large cluster,
> we met more than 100 nodes were dead, decommissioning and their {panel} Under
> replicated blocks {panel} {panel} Blocks with no live replicas {panel} were
> all ZERO. Actually It has been fixed in
> [HDFS-7374|https://issues.apache.org/jira/browse/HDFS-7374]. After that, we
> can refreshNode twice to eliminate this case. But, seems this patch missed
> after refactor[HDFS-7411|https://issues.apache.org/jira/browse/HDFS-7411]. We
> are using a Hadoop version based 2.7.1 and only below operations can
> transition the status from {panel} Dead, DECOMMISSION_INPROGRESS {panel} to
> {panel} Dead, DECOMMISSIONED {panel}:
> # Retire it from hdfs-exclude
> # refreshNodes
> # Re-add it to hdfs-exclude
> # refreshNodes
> So, why the code removed after refactor in the new DecommissionManager?
> {code:java}
> if (!node.isAlive) {
> LOG.info("Dead node " + node + " is decommissioned immediately.");
> node.setDecommissioned();
> {code}
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