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From "Arpit Agarwal (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HDFS-12420) Disable Namenode format when data already exists
Date Wed, 13 Sep 2017 19:44:01 GMT

    [ https://issues.apache.org/jira/browse/HDFS-12420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16165177#comment-16165177
] 

Arpit Agarwal edited comment on HDFS-12420 at 9/13/17 7:43 PM:
---------------------------------------------------------------

Allen, thanks for bringing up the automation concern. We certainly don't want to break any
deployment scripts. This patch will not break scripted deployment of new clusters since it
eliminates the prompt completely.

Formatting clusters with pre-existing data was a bad idea in the first place. It deletes the
NameNode metadata and leaves the cluster in an unusable state since DataNodes cannot connect
anymore. I don't think any existing automation can depend on this behavior since it is functionally
broken.

That said, if you have examples of automated deployments that will be broken by this change
and that we haven't thought of, we can abandon the idea.


was (Author: arpitagarwal):
Allen, thanks for bringing up the automation concern. We certainly don't want to break any
deployment scripts. This patch will not break scripted deployment of new clusters since it
eliminates the prompt completely.

Formatting clusters with pre-existing data was a bad idea in the first place. It deletes the
NameNode metadata and leaves the cluster in an unusable state since DataNodes cannot connect
anymore. I don't think any existing automation can depend on this behavior since it is functionally
broken.

> 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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