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https://issues.apache.org/jira/browse/HDFS-13596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16813327#comment-16813327
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star commented on HDFS-13596:
-----------------------------

New properties will be ignored as I checked the code. There ls a length field 
in every edit log.  To write new properties after older ones is not just about 
this issue, but a rule for future extension. If not, there's high risks that 
hdfs metadata being broken after finanizing. Because until then new properties 
are written in editlogs, which is not verified in the process of rolling 
upgrade. Metadata will not be recoverable at that time. Maybe I 'm wrong on 
this, feel free to correct.

> NN restart fails after RollingUpgrade from 2.x to 3.x
> -----------------------------------------------------
>
>                 Key: HDFS-13596
>                 URL: https://issues.apache.org/jira/browse/HDFS-13596
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs
>            Reporter: Hanisha Koneru
>            Assignee: Fei Hui
>            Priority: Critical
>         Attachments: HDFS-13596.001.patch, HDFS-13596.002.patch, 
> HDFS-13596.003.patch, HDFS-13596.004.patch
>
>
> After rollingUpgrade NN from 2.x and 3.x, if the NN is restarted, it fails 
> while replaying edit logs.
>  * After NN is started with rollingUpgrade, the layoutVersion written to 
> editLogs (before finalizing the upgrade) is the pre-upgrade layout version 
> (so as to support downgrade).
>  * When writing transactions to log, NN writes as per the current layout 
> version. In 3.x, erasureCoding bits are added to the editLog transactions.
>  * So any edit log written after the upgrade and before finalizing the 
> upgrade will have the old layout version but the new format of transactions.
>  * When NN is restarted and the edit logs are replayed, the NN reads the old 
> layout version from the editLog file. When parsing the transactions, it 
> assumes that the transactions are also from the previous layout and hence 
> skips parsing the erasureCoding bits.
>  * This cascades into reading the wrong set of bits for other fields and 
> leads to NN shutting down.
> Sample error output:
> {code:java}
> java.lang.IllegalArgumentException: Invalid clientId - length is 0 expected 
> length 16
>  at com.google.common.base.Preconditions.checkArgument(Preconditions.java:88)
>  at org.apache.hadoop.ipc.RetryCache$CacheEntry.<init>(RetryCache.java:74)
>  at org.apache.hadoop.ipc.RetryCache$CacheEntry.<init>(RetryCache.java:86)
>  at 
> org.apache.hadoop.ipc.RetryCache$CacheEntryWithPayload.<init>(RetryCache.java:163)
>  at 
> org.apache.hadoop.ipc.RetryCache.addCacheEntryWithPayload(RetryCache.java:322)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.addCacheEntryWithPayload(FSNamesystem.java:960)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.applyEditLogOp(FSEditLogLoader.java:397)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:249)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:158)
>  at org.apache.hadoop.hdfs.server.namenode.FSImage.loadEdits(FSImage.java:888)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:745)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:323)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFSImage(FSNamesystem.java:1086)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:714)
>  at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:632)
>  at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:694)
>  at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:937)
>  at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:910)
>  at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1643)
>  at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1710)
> 2018-05-17 19:10:06,522 WARN 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Encountered exception 
> loading fsimage
> java.io.IOException: java.lang.IllegalStateException: Cannot skip to less 
> than the current value (=16389), where newValue=16388
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.resetLastInodeId(FSDirectory.java:1945)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:298)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:158)
>  at org.apache.hadoop.hdfs.server.namenode.FSImage.loadEdits(FSImage.java:888)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:745)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:323)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFSImage(FSNamesystem.java:1086)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:714)
>  at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:632)
>  at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:694)
>  at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:937)
>  at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:910)
>  at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1643)
>  at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1710)
> Caused by: java.lang.IllegalStateException: Cannot skip to less than the 
> current value (=16389), where newValue=16388
>  at org.apache.hadoop.util.SequentialNumber.skipTo(SequentialNumber.java:58)
>  at 
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.resetLastInodeId(FSDirectory.java:1943)
> {code}



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