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https://issues.apache.org/jira/browse/HADOOP-7458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13066323#comment-13066323
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Gerrit Jansen van Vuuren commented on HADOOP-7458:
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Of course you can write.
Once the namenode reads the edit logs and merges the valid entries into the
image file your good to go.
I say put it in safe mode because that way you can validate.
After validation nothing stops you from putting the namenode out of safe mode.
The problem is if you don't have a secondary namenode checkpoint because for
some reason the secondary namenode failed
silently. This was my case a couple of days ago, and I managed via the method
above to recover all of my data, the cluster is now running writing and
reading. With the other alternatives provided in this jira and other mailing
lists I would've lost all data.
Yes I know the issue is invalidated but I strongly disagree with that. Why is
the need to recover from a corrupt edits log invalid????? Its not enough to
just say: oh you should have had backups.
Especially when a simple alternative exists, and the namenode has the ability
to recover from it.
I would strongly insist to reopen this issue, especially when a fix does exist.
> Namenode not get started! FSNamesystem initialization failed.
> java.io.FileNotFoundException
> -------------------------------------------------------------------------------------------
>
> Key: HADOOP-7458
> URL: https://issues.apache.org/jira/browse/HADOOP-7458
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 0.20.2
> Environment: CentOS release 5.5 (Final), 18 node Cluster
> Reporter: Sakthivel Murugasamy
> Priority: Blocker
> Labels: hadoop
> Original Estimate: 48h
> Remaining Estimate: 48h
>
> 2011-07-13 12:04:12,967 ERROR
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem
> initialization failed.
> java.io.FileNotFoundException: File does not exist:
> /opt/data/tmp/mapred/system/job_201107041958_0120/j^@^@^@^@^@^@
> at
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.unprotectedSetPermission(FSDirectory.java:544)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLog.loadFSEdits(FSEditLog.java:724)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSEdits(FSImage.java:992)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:812)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:364)
> at
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:87)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:311)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:292)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:201)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:279)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:956)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:965)
> 2011-07-13 12:04:13,006 ERROR
> org.apache.hadoop.hdfs.server.namenode.NameNode:
> java.io.FileNotFoundException: File does not exist:
> /opt/data/tmp/mapred/system/job_201107041958_0120/j^@^@^@^@^@^@
> at
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.unprotectedSetPermission(FSDirectory.java:544)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLog.loadFSEdits(FSEditLog.java:724)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSEdits(FSImage.java:992)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:812)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:364)
> at
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:87)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:311)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:292)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:201)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:279)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:956)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:965)
> In the path /opt/data/tmp/mapred, "system/" folder itself is not available
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