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https://issues.apache.org/jira/browse/HDFS-2026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13049606#comment-13049606
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Todd Lipcon commented on HDFS-2026:
-----------------------------------
I should note that the patch does *not* add a "-format" command to the 2NN yet.
I'll do that separately to keep this an easy review.
> 1073: 2NN needs to handle case of reformatted NN better
> -------------------------------------------------------
>
> Key: HDFS-2026
> URL: https://issues.apache.org/jira/browse/HDFS-2026
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: name-node
> Affects Versions: Edit log branch (HDFS-1073)
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Critical
> Fix For: Edit log branch (HDFS-1073)
>
> Attachments: hdfs-2026.txt
>
>
> Currently in the 1073 branch, the following steps ends up with a very
> confused 2NN:
> - format NN, run NN
> - start 2NN, perform some checkpoints
> - reformat NN, start NN on new namespace
> - restart same 2NN
> The 2NN currently saves the new VERSION info into its local storage directory
> but doesn't clear out the old checkpoint or edits files. This is obviously
> wrong and might lead to a corrupt checkpoint getting uploaded.
> If the 2NN has storage directories with VERSION info, and connects to an NN
> with different VERSION info, there are two alternatives:
> a) refuse to perform any checkpoints until the operator issues a
> "secondarynamenode -format" command (this is similar to how the
> backupnode/checkpointnode works)
> b) clear the current contents of the storage directory and save the new NN's
> VERSION info.
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