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Scenario: Local HDFS stuck in safe mode on Azure HDInsight cluster

  • Grein

This article describes troubleshooting steps and possible resolutions for issues when interacting with Azure HDInsight clusters.

Issue

The local Apache Hadoop Distributed File System (HDFS) is stuck in safe mode on the HDInsight cluster. You receive an error message similar as follows:

hdiuser@spark2:~$ hdfs dfs -D "fs.default.name=hdfs://mycluster/" -mkdir /temp
17/04/05 16:20:52 WARN retry.RetryInvocationHandler: Exception while invoking ClientNamenodeProtocolTranslatorPB.mkdirs over spark2.2oyzcdm4sfjuzjmj5dnmvscjpg.dx.internal.cloudapp.net/10.0.0.22:8020. Not retrying because try once and fail.
org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.server.namenode.SafeModeException): Cannot create directory /temp. Name node is in safe mode.
It was turned on manually. Use "hdfs dfsadmin -safemode leave" to turn safe mode off.
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkNameNodeSafeMode(FSNamesystem.java:1359)
...
mkdir: Cannot create directory /temp. Name node is in safe mode.

Cause

The HDInsight cluster has been scaled down to very few nodes below, or number of nodes is close to the HDFS replication factor.

Resolution

  1. Report on the status of HDFS on the HDInsight cluster with the following command:

    hdfs dfsadmin -D "fs.default.name=hdfs://mycluster/" -report

  2. Check on the integrity of HDFS on the HDInsight cluster with the following command:

    hdiuser@spark2:~$ hdfs fsck -D "fs.default.name=hdfs://mycluster/" /

  3. If determined there are no missing, corrupt or under replicated blocks or those blocks can be ignored run the following command to take the name node out of safe mode:

    hdfs dfsadmin -D "fs.default.name=hdfs://mycluster/" -safemode leave

Next steps

If you didn't see your problem or are unable to solve your issue, visit one of the following channels for more support:

  • Get answers from Azure experts through Azure Community Support.

  • Connect with @AzureSupport - the official Microsoft Azure account for improving customer experience. Connecting the Azure community to the right resources: answers, support, and experts.

  • If you need more help, you can submit a support request from the Azure portal. Select Support from the menu bar or open the Help + support hub. For more detailed information, review How to create an Azure support request. Access to Subscription Management and billing support is included with your Microsoft Azure subscription, and Technical Support is provided through one of the Azure Support Plans.