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Date: Wed, 16 Nov 2016 01:20:58 +0000 (UTC)
From: "Yiqun Lin (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.13017061.1478048943000.287737.1479259258585@Atlassian.JIRA>
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Subject: [jira] [Commented] (HDFS-11090) Leave safemode immediately if all
 blocks have reported in
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archived-at: Wed, 16 Nov 2016 01:21:00 -0000


    [ https://issues.apache.org/jira/browse/HDFS-11090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15668959#comment-15668959 ] 

Yiqun Lin commented on HDFS-11090:
----------------------------------

Agree with the [~andrew.wang]. If we are sure to make a change, I think it's better to improve the logic of leaving safemode when there is "empty cluster".

> Leave safemode immediately if all blocks have reported in
> ---------------------------------------------------------
>
>                 Key: HDFS-11090
>                 URL: https://issues.apache.org/jira/browse/HDFS-11090
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode
>    Affects Versions: 2.7.3
>            Reporter: Andrew Wang
>            Assignee: Yiqun Lin
>         Attachments: HDFS-11090.001.patch
>
>
> Startup safemode is triggered by two thresholds: % blocks reported in, and min # datanodes. It's extended by an interval (default 30s) until these two thresholds are met.
> Safemode extension is helpful when the cluster has data, and the default % blocks threshold (0.99) is used. It gives DNs a little extra time to report in and thus avoid unnecessary replication work.
> However, we can leave startup safemode early if 100% of blocks have reported in.
> Note that operators sometimes change the % blocks threshold to > 1 to never automatically leave safemode. We should maintain this behavior.


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