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NN stopped and cannot recover with error "There appears to be a gap in the edit log"

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NN stopped and cannot recover with error "There appears to be a gap in the edit log"

New Contributor

Hi there,

 

I deployed a single node for CDH and CM for testing, however once I added some services like Hub, the NN stopped and cannot start it with eror: There appears to be a gap in the edit log.

 

2013-11-14 15:00:01,431 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system shutdown complete.
2013-11-14 15:00:01,432 FATAL org.apache.hadoop.hdfs.server.namenode.NameNode: Exception in namenode join
java.io.IOException: There appears to be a gap in the edit log.  We expected txid 8364, but got txid 27381.
	at org.apache.hadoop.hdfs.server.namenode.MetaRecoveryContext.editLogLoaderPrompt(MetaRecoveryContext.java:94)
	at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:158)
	at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:92)
	at org.apache.hadoop.hdfs.server.namenode.FSImage.loadEdits(FSImage.java:744)
	at org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:660)
	at org.apache.hadoop.hdfs.server.namenode.FSImage.doUpgrade(FSImage.java:349)
	at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:261)
	at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFSImage(FSNamesystem.java:639)
	at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:476)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:403)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:437)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.(NameNode.java:613)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.(NameNode.java:598)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1169)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1233)
2013-11-14 15:00:01,445 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1
2013-11-14 15:00:01,448 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG: 
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at ubcdh/10.0.0.4
************************************************************/

 

I tied to run "./bin/hadoop namenode -recover" however it was returned another error:

 

13/11/14 14:52:17 INFO hdfs.StateChange: STATE* Safe mode is ON.
Use "hdfs dfsadmin -safemode leave" to turn safe mode off.

 However the command to leave safemode with error:

 

safemode: Call From ubcdh/10.0.0.4 to ubcdh:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused

 

 

All my services are running porperly and only one node configured, so I don't think the connection is in failure status.

 

How can I get this issue fixed?

1 ACCEPTED SOLUTION

Accepted Solutions

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Expert Contributor

Your edit log transactions are missing in the namenode metadata directory....

 

"We expected txid 8364, but got txid 27381" ---this mean the edit logs/transactions from 8364 to 27381 are missing....If you don't want to loose the data restore the edit logs from back up metadata if you have or just point the namenode to txid 27381, you may loose data if you point namenode to txid 27381.

 

Em Jay
8 REPLIES 8

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Master Collaborator

@JUNXIONG I have moved this post to the HDFS discussion board since this is an HDFS specific issue.  Hopefully someone in here can assist you.

 

Regards

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Expert Contributor

Your edit log transactions are missing in the namenode metadata directory....

 

"We expected txid 8364, but got txid 27381" ---this mean the edit logs/transactions from 8364 to 27381 are missing....If you don't want to loose the data restore the edit logs from back up metadata if you have or just point the namenode to txid 27381, you may loose data if you point namenode to txid 27381.

 

Em Jay

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

New Contributor
Thank you Manikumar, I think I can understand what issue is now. So how that issue happen? What's the common causes of it?

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Expert Contributor

I think this happens when you try to format the namenode....

Em Jay

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Explorer

Would someone be kind enough to describe the process of "just point the namenode to txid 27381"? I've been having this issue on a fresh HDFS cluster, and this sounds like an easy way to fix it.

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Explorer

Hi Mythobeast, 

Do you have the procedure to resolve this issue?

Highlighted

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

New Contributor

How to point namenode particular txid ? 

Re: NN stopped and cannot recover with error "There appears to be a gap in the edit log"

Explorer

Hi, I have the same error, " we expected   txid xxxx , but got yyyy"

How do I change the pointer of the namenode? 

Please advice. 

Thanks

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