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https://issues.apache.org/jira/browse/HDFS-2026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13052837#comment-13052837
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Eli Collins commented on HDFS-2026:
-----------------------------------
Looks great.
Some small stuff:
* Can we remove Checkpointer#uploadCheckpoint commented out? (mark TODO if
addressed in follow-on)
* testReformatNNBetweenCheckpoints method comment is missing a period.
* The new call to sd.read in SecondaryNameNode#recoverCreate could use a
comment (not clear why we need to read the version file there). As an aside,
readVersionFile would be a better name for that method.
* Not you change would be good to add a comment to uploadImageFromStorage
indicating it doesn't actually post an image but the 2NN posts to the NN asking
it to get an image.
> 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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