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From "Uma Maheswara Rao G (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2747) HA: entering safe mode after starting SBN can NPE
Date Thu, 12 Jan 2012 15:31:39 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13185016#comment-13185016
] 

Uma Maheswara Rao G commented on HDFS-2747:
-------------------------------------------

Here the reason for NullPoniterException is, initially when we are entering into safemode,
editLogStream will be null in FSEditlog because there is no log segment started yet.

The reason for success of second time safemode entering is, The same synctxtid already visited
once with previous safemode trail. So it will assume that this transaction was already flushed
and will return. There won't be any exception in logSyncAll call and will enter into safemode
successfully again.

java.lang.NullPointerException
	at org.apache.hadoop.hdfs.server.namenode.FSEditLog.logSync(FSEditLog.java:524)
	at org.apache.hadoop.hdfs.server.namenode.FSEditLog.logSyncAll(FSEditLog.java:450)
	at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.enterSafeMode(FSNamesystem.java:3780)
	at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.setSafeMode(FSNamesystem.java:3648)
	at org.apache.hadoop.hdfs.server.namenode.FSImageTestUtil.enterSafemode(FSImageTestUtil.java:510)
	



                
> HA: entering safe mode after starting SBN can NPE
> -------------------------------------------------
>
>                 Key: HDFS-2747
>                 URL: https://issues.apache.org/jira/browse/HDFS-2747
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: ha
>    Affects Versions: HA branch (HDFS-1623)
>            Reporter: Eli Collins
>            Assignee: Uma Maheswara Rao G
>
> Entering Safemode on the primary after while it's already in safemode after the SBN is
started results in an NPE: 
> {noformat}
> hadoop-0.24.0-SNAPSHOT $ ./bin/hdfs dfsadmin -safemode get
> Safe mode is ON
> hadoop-0.24.0-SNAPSHOT $ ./bin/hdfs dfsadmin -safemode enter
> safemode: java.lang.NullPointerException
> {noformat}

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