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https://issues.apache.org/jira/browse/HDFS-6353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14380993#comment-14380993
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Jing Zhao commented on HDFS-6353:
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Had an offline discussion with Suresh and Jitendra. What we can do is:
# add a flag to allow users to disable the feature
# in the shell script, check the return value of saveNamespace command, and if
it fails, print error/hint msg and exit
We can do this in a follow up jira in trunk before merging the feature into
branch-2.
> Check and make checkpoint before stopping the NameNode
> ------------------------------------------------------
>
> Key: HDFS-6353
> URL: https://issues.apache.org/jira/browse/HDFS-6353
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Suresh Srinivas
> Assignee: Jing Zhao
> Fix For: 3.0.0
>
> Attachments: HDFS-6353.000.patch, HDFS-6353.001.patch,
> HDFS-6353.002.branch-2.patch, HDFS-6353.002.branch-2.patch,
> HDFS-6353.002.patch
>
>
> One of the failure patterns I have seen is, in some rare circumstances, due
> to some inconsistency the secondary or standby fails to consume editlog. The
> only solution when this happens is to save the namespace at the current
> active namenode. But sometimes when this happens, unsuspecting admin might
> end up restarting the namenode, requiring more complicated solution to the
> problem (such as ignore editlog record that cannot be consumed etc.).
> How about adding the following functionality:
> When checkpointer (standby or secondary) fails to consume editlog, based on a
> configurable flag (on/off) to let the active namenode know about this
> failure. Active namenode can enters safemode and saves namespace. When in
> this type of safemode, namenode UI also shows information about checkpoint
> failure and that it is saving namespace. Once the namespace is saved,
> namenode can come out of safemode.
> This means service unavailability (even in HA cluster). But it might be worth
> it to avoid long startup times or need for other manual fixes. Thoughts?
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