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Posted to hdfs-issues@hadoop.apache.org by "Xiaoqiao He (Jira)" <ji...@apache.org> on 2026/07/16 09:14:00 UTC
[jira] [Commented] (HDFS-17952) standby namenode restart,datanode failed to connect
[ https://issues.apache.org/jira/browse/HDFS-17952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18096720#comment-18096720 ]
Xiaoqiao He commented on HDFS-17952:
------------------------------------
Thanks [~Jepon] for your report. I think the main issue is that JVM can't find the classpath file after you move jar file but not restart datanode. So it throws NoClassDefFoundError. BTW, please send mail to maillist here https://hadoop.apache.org/mailing_lists.html first.
Will close this ticket. Please feel free to reopen it if make sure this is one issue. Thanks again.
> standby namenode restart,datanode failed to connect
> ----------------------------------------------------
>
> Key: HDFS-17952
> URL: https://issues.apache.org/jira/browse/HDFS-17952
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Affects Versions: 2.9.2
> Reporter: Jepon
> Priority: Major
>
> {*}{color:#4c9aff}Environment：{color}{*}1、Back up all nodes' $HADOOP_HOME/share/hadoop/hdfs/hadoop-hdfs-2.9.2.jar files directly to bak and upload the latest jar file.
> 2、Apache Hadoop 2.9.2 setup with two Namenode nodes (NN1 as standby, NN2 as active).
> *After restarting NN1, the system shows 83 DN nodes with 82 successfully registered DN links, but one DN node fails to establish a connection with NN1, triggering an error:*
> 2026-07-13 18:24:12,159 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:13,159 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 1 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:14,159 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 2 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:15,160 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 3 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:16,160 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 4 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:17,160 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 5 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:18,161 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 6 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:19,161 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 7 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:20,162 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 8 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:21,162 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: bdpprd01/10.1.1.1:9000. Already tried 9 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
> 2026-07-13 18:24:22,492 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Unexpected exception in block pool Block pool BP-383332234-10.1.1.1-1584640173217 (Datanode Uuid 213c4874-89c5-40d5-8a61-db4dbcd0439c) service to bdpprd01/10.1.1.1:9000
> {color:#de350b}java.lang.NoClassDefFoundError: org/apache/hadoop/hdfs/protocol/UnregisteredNodeException{color}
> at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:717)
> at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:841)
> at java.lang.Thread.run(Thread.java:748)
> 2026-07-13 18:24:22,492 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Ending block pool service for: Block pool BP-383332234-10.1.1.1-1584640173217 (Datanode Uuid 213c4874-89c5-40d5-8a61-db4dbcd0439c) service to bdpprd01/10.1.1.1:9000
> But，Check the bak Jar's source code; this {color:#de350b}UnregisteredNodeException {color}class exists.
> Why?
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