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https://issues.apache.org/jira/browse/HDFS-12420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16165023#comment-16165023
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Anu Engineer commented on HDFS-12420:
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bq. Don't we already have the y/n check when data exists? Why do we need
another?
We do, but the fact that it not very clear with lots of other text on the
screen was pointed out by a cluster owner, who was visibly distressed.
We are just trying to avoid losing data by operator mistake. I thought that you
might have a concern with automation that is why I flagged it for your
consideration. Let me try to understand that a bit more, do you think people
automate formatting the clusters? if they do, then preventing accidental data
loss is all the more important.
>From an HDFS user hat on, I think this is a good improvement to have. I would
>expect HDFS to refuse to format a cluster with data. But from a
>sysadmin/developer hat on, I do like that fact that I can format a cluster
>with data. I do that when I test and develop.
So in my mind, the question boils down to easier dev/ops cycles vs. user
safety. The reason why this is filed for 3.0 is that it might be our last
opportunity to make this change.
bq. Completely breaks automation. Automation MUST work.
I see that you are voting with the devops hat on, and I do not disagree. But
this is a place where breaking the automation might avoid a disaster for some
poor user. One more data point, this JIRA is based on real feedback from a real
large cluster. I am not apologizing for sloppy operation but trying to
understand what we can do to prevent a user from making such a mistake.
I am presuming (please correct me if I am wrong) that you are not objecting to
the change or the intent per se, but more about the fact that we are out right
refusing to format a cluster with Namenode metadata. Do you think adding a flag
which says *-DothisIamReallySmart* address the automation concern?
> Disable Namenode format when data already exists
> ------------------------------------------------
>
> Key: HDFS-12420
> URL: https://issues.apache.org/jira/browse/HDFS-12420
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Ajay Kumar
> Assignee: Ajay Kumar
> Attachments: HDFS-12420.01.patch, HDFS-12420.02.patch
>
>
> Disable NameNode format to avoid accidental formatting of Namenode in
> production cluster. If someone really wants to delete the complete fsImage,
> they can first delete the metadata dir and then run {code} hdfs namenode
> -format{code} manually.
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