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https://issues.apache.org/jira/browse/HDFS-13596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16813548#comment-16813548
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Daryn Sharp commented on HDFS-13596:
------------------------------------
I'm really glad this has gained traction! Otherwise 3.x hdfs was DOA...
{quote} New properties will be ignored as I checked the code. There ls a
length field in every edit log.
{quote}
I can't remember exact details but when I tried to take advantage of this
behavior in ~2.6-2.7 it was completely broken so might double check.
# The check for EC support should be in {{FSNamesystem}} methods, not
{{NameNodeRpcServer}}, since there can be multiple entry points to the
namesystem like webhdfs.
# {{DFSUtil.isSupportedErasureCoding}} probably doesn't belong in {{DFSUtil}}
since it's not something that should called outside of the NN.
# In {{FSEditLogOp}}, please call the former method instead of duplicating the
logic.
# Super trivial, might rename new {{layoutVersion}} parameter in the write
methods to {{logVersion}} to be consistent with the signatures for the read
methods.
# How about a {{FSNamesystem.checkErasureCodingSupported(String op)}} to avoid
all the redundant check/throw code in the methods?
# A test case is needed to prove the edits are correctly read/written.
> 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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