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https://issues.apache.org/jira/browse/HDFS-5443?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13813722#comment-13813722
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Vinay commented on HDFS-5443:
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Hi Uma,
problem of 0-sized blocks is there with normal files also (HDFS-4516), but that
will not cause in NN safemode because file will be an under construction file
and 0-sized block will not be counted in safemode threshold.
Here actual problem is not containing the 0-sized blocks, but counting them
also in safemode threshold as these are loaded as COMPLETE blocks
{quote}If the file is already an INodeFileUnderConstructionWithSnapshot, the
current code will finally call collectBlocksAndClear and remove the 0-sized
block.
If the file is just an INodeFileUC (but not INodeUCWithSnapshot), when we
delete its parent directory or ancestral directory, the current code will do
nothing and leave the 0-sized block there.{quote}
HDFS-5428 handles above scenarios as well.
[~sathish.gurram] Can you verify the same scenario with the latest patch in
HDFS-5428
> Namenode can stuck in safemode on restart if it crashes just after addblock
> logsync and after taking snapshot for such file.
> ----------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-5443
> URL: https://issues.apache.org/jira/browse/HDFS-5443
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: snapshots
> Affects Versions: 3.0.0, 2.2.0
> Reporter: Uma Maheswara Rao G
> Assignee: sathish
>
> This issue is reported by Prakash and Sathish.
> On looking into the issue following things are happening.
> .
> 1) Client added block at NN and just did logsync
> So, NN has block ID persisted.
> 2)Before returning addblock response to client take a snapshot for root or
> parent directories for that file
> 3) Delete parent directory for that file
> 4) Now crash the NN with out responding success to client for that addBlock
> call
> Now on restart of the Namenode, it will stuck in safemode.
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