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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5474) Deletesnapshot can make Namenode in safemode on NN restarts.
Date Wed, 13 Nov 2013 01:23:18 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13820781#comment-13820781
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Jing Zhao commented on HDFS-5474:
---------------------------------

BTW, please rebase the patch and upload the patch for trunk :)

> Deletesnapshot can make Namenode in safemode on NN restarts.
> ------------------------------------------------------------
>
>                 Key: HDFS-5474
>                 URL: https://issues.apache.org/jira/browse/HDFS-5474
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: snapshots
>            Reporter: Uma Maheswara Rao G
>            Assignee: sathish
>         Attachments: HDFS-5474-001.patch
>
>
> When we deletesnapshot, we are deleting the blocks associated to that snapshot and after
that we do logsync to editlog about deleteSnapshot.
> There can be a chance that blocks removed from blocks map but before log sync if there
is BR ,  NN may finds that block does not exist in blocks map and may invalidate that block.
As part HB, invalidation info also can go. After this steps if Namenode shutdown before actually
do logsync,  On restart it will still consider that snapshot Inodes and expect blocks to report
from DN.
> Simple solution is, we should simply move down that blocks removal after logsync only.
Similar to delete op.



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