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From "Vinay (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5504) In HA mode, OP_DELETE_SNAPSHOT is not decrementing the safemode threshold, leads to NN safemode.
Date Wed, 13 Nov 2013 01:09:17 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13820767#comment-13820767
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Vinay commented on HDFS-5504:
-----------------------------

Hi Jing,
Thanks for reviewing the patch.
I thought about keeping the old code in {{removePathAndBlocks()}}. When we see the code, locking
will happen only during loading edits. This can be only in startup or while tailing edits
in SNN. So locking and unlocking again for every 1000 blocks may not be problem in my opinion.

If still require updation, I will upload the patch addressing this.

> In HA mode, OP_DELETE_SNAPSHOT is not decrementing the safemode threshold, leads to NN
safemode.
> ------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-5504
>                 URL: https://issues.apache.org/jira/browse/HDFS-5504
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: snapshots
>    Affects Versions: 3.0.0, 2.2.0
>            Reporter: Vinay
>            Assignee: Vinay
>         Attachments: HDFS-5504.patch
>
>
> 1. HA installation, standby NN is down.
> 2. delete snapshot is called and it has deleted the blocks from blocksmap and all datanodes.
log sync also happened.
> 3. before next log roll NN crashed
> 4. When the namenode restartes then it will fsimage and finalized edits from shared storage
and set the safemode threshold. which includes blocks from deleted snapshot also. (because
this edits is not yet read as namenode is restarted before the last edits segment is not finalized)
> 5. When it becomes active, it finalizes the edits and read the delete snapshot edits_op.
but at this time, it was not reducing the safemode count. and it will continuing in safemode.
> 6. On next restart, as the edits is already finalized, on startup only it will read and
set the safemode threshold correctly.
> But one more restart will bring NN out of safemode.



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