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https://issues.apache.org/jira/browse/HDFS-2815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13202036#comment-13202036
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Uma Maheswara Rao G commented on HDFS-2815:
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Ok, thanks todd.
It seems to me that, In older versions,we always deletes before syncing. As
part of the HDFS-173, we are deleting the blocks before syncing if they are
less than or equal to the BLOCK_DELETION_INCREMENT. Default 1000.
I guess HDFS-173 is to solve the large block deletes. SO, might not intended to
change the behaviour with smaller deletes.
Yes, Suresh can confirm the exact reason for this.
Also offline, Suresh confirmed that he will take a look soon.
> Namenode is not coming out of safemode when we perform ( NN crash + restart )
> . Also FSCK report shows blocks missed.
> ----------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-2815
> URL: https://issues.apache.org/jira/browse/HDFS-2815
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 0.22.0, 0.24.0, 0.23.1, 1.0.0
> Reporter: Uma Maheswara Rao G
> Assignee: Uma Maheswara Rao G
> Priority: Critical
> Attachments: HDFS-2815.patch
>
>
> When tested the HA(internal) with continuous switch with some 5mins gap,
> found some *blocks missed* and namenode went into safemode after next switch.
>
> After the analysis, i found that this files already deleted by clients.
> But i don't see any delete commands logs namenode log files. But namenode
> added that blocks to invalidateSets and DNs deleted the blocks.
> When restart of the namenode, it went into safemode and expecting some
> more blocks to come out of safemode.
> Here the reason could be that, file has been deleted in memory and added
> into invalidates after this it is trying to sync the edits into editlog file.
> By that time NN asked DNs to delete that blocks. Now namenode shuts down
> before persisting to editlogs.( log behind)
> Due to this reason, we may not get the INFO logs about delete, and when we
> restart the Namenode (in my scenario it is again switch), Namenode expects
> this deleted blocks also, as delete request is not persisted into editlog
> before.
> I reproduced this scenario with bedug points. *I feel, We should not add
> the blocks to invalidates before persisting into Editlog*.
> Note: for switch, we used kill -9 (force kill)
> I am currently in 0.20.2 version. Same verified in 0.23 as well in normal
> crash + restart scenario.
>
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