Handling YARN resources manager issue with decommissioned nodes

If you hit the following exception with your YARN resource manager:


17/07/31 15:06:13 WARN retry.RetryInvocationHandler: Exception while invoking class org.apache.hadoop.yarn.api.impl.pb.client.ApplicationClientProtocolPBClientImpl.getClusterNodes over rm1. Not retrying because try once and fail.
java.lang.ClassCastException: org.apache.hadoop.yarn.server.resourcemanager.NodesListManager$UnknownNodeId cannot be cast to org.apache.hadoop.yarn.api.records.impl.pb.NodeIdPBImpl


Please try running the following command and you will see the exact same exception:

$ yarn node -list -all

Root Cause:

This problem happen when your YARN cluster have decommissioned nodes and it could cause issue with other dependent application i.e. H2O to not to start.


Please make sure all the decommissioned nodes are either not listed or added back as full service nodes.
That’s it, enjoy!!

Setting various logs levels for H2O

Setting log levels in different H2O deployment scenarios.

Standalone H2O mode (H2O on VMs, laptops…)

You can specify options -log_level and/or -log_dir:

Write messages at this logging level, or above. Default is INFO.
-log_dir <fileSystemPath>

The directory where H2O writes logs to disk. (This usually has a good default that you need not change.)

$ java -jar h2o.jar -log_level DEBUG

H2O on Hadoop

The log level option is not directly exposed. You can still set the log level by adding an extra java argument using the -J option of the Hadoop h2o driver: “-J -log_level -J DEBUG”. Here is an example:

$ hadoop jar h2odriver.jar -J -log_level -J DEBUG -nodes 1 -mapperXmx 1g -output t/$RANDOM

Sparkling Water:

Log levels can be adjusted using Spark conf properties: spark.ext.h2o.node.log.level and spark.ext.h2o.client.log.level, these are two separate options for the compute node and the h2o client running in Sparkling Water’s driver program (H2O client).

$ bin/sparkling-shell --conf spark.ext.h2o.node.log.level=DEBUG --conf spark.ext.h2o.client.log.level=DEBUG

Free ebook: Introducing Microsoft Azure HDInsight

New Free eBook by Microsoft Press:

Microsoft Press is thrilled to share another new free ebook with you:Introducing Microsoft Azure HDInsight, by Avkash Chauhan, Valentine Fontama, Michele Hart, Wee Hyong Tok, and Buck Woody. 


Free ebook: Introducing Microsoft Azure HDInsight

Introduction (excerpt)

Microsoft Azure HDInsight is Microsoft’s 100 percent compliant distribution of Apache Hadoop on Microsoft Azure. This means that standard Hadoop concepts and technologies apply, so learning the Hadoop stack helps you learn the HDInsight service. At the time of this writing, HDInsight (version 3.0) uses Hadoop version 2.2 and Hortonworks Data Platform 2.0.

In Introducing Microsoft Azure HDInsight, we cover what big data really means, how you can use it to your advantage in your company or organization, and one of the services you can use to do that quickly—specifically, Microsoft’s HDInsight service. We start with an overview of big data and Hadoop, but we don’t emphasize only concepts in this book—we want you to jump in and get your hands dirty working with HDInsight in a practical way. To help you learn and even implement HDInsight right away, we focus on a specific use case that applies to almost any organization and demonstrate a process that you can follow along with.

We also help you learn more. In the last chapter, we look ahead at the future of HDInsight and give you recommendations for self-learning so that you can dive deeper into important concepts and round out your education on working with big data.

Here are the download links (and below the links you’ll find an ebook excerpt that describes this offering):

Download the PDF (6.37 MB; 130 pages) fromhttp://aka.ms/IntroHDInsight/PDF

Download the EPUB (8.46 MB) fromhttp://aka.ms/IntroHDInsight/EPUB

Download the MOBI (12.8 MB) fromhttp://aka.ms/IntroHDInsight/MOBI

Download the code samples (6.83 KB) fromhttp://aka.ms/IntroHDInsight/CompContent

Troubleshooting Cloudera Manager installation and start issues

After Cloudera Manager is installed and running you can access it over the web UI through <Your_IP_Address>:7180 , if you could not access it, then here are few ways to troubleshoot the problem. These details are helpful with you are installing Cloudera Hadoop on a remotely located machine and you just have shell access to that machine over SSH.

Verify if Cloudera Manager is running: 

[root@cloudera-master ~]# service cloudera-scm-server status
cloudera-scm-server (pid 4652) is running…

Now lets check the Cloudera Manager logs for further verification:

[root@cloudera-master ~]# ps -ef | grep cloudera-scm
498        977     1  0 16:31 ?        00:00:01 /usr/bin/postgres -D /var/lib/cloudera-scm-server-db/data
root      3729     1  0 16:59 pts/0    00:00:00 su cloudera-scm -s /bin/bash -c nohup /usr/sbin/cmf-server
498       3731  3729 53 16:59 ?        00:00:47 /usr/java/jdk1.6.0_31/bin/java -cp .:lib/*:/usr/share/java/mysql-connector-java.jar -Dlog4j.configuration=file:/etc/cloudera-scm-server/log4j.properties -Dcmf.root.logger=INFO,LOGFILE -Dcmf.log.dir=/var/log/cloudera-scm-server -Dcmf.log.file=cloudera-scm-server.log -Dcmf.jetty.threshhold=WARN -Dcmf.schema.dir=/usr/share/cmf/schema -Djava.awt.headless=true -Djava.net.preferIPv4Stack=true -Dpython.home=/usr/share/cmf -Xmx2G -XX:MaxPermSize=256m com.cloudera.server.cmf.Main
root      3835  1180  0 17:00 pts/0    00:00:00 grep cloudera-scm

You can access Cloudera Manager Logs located as below (as shown in the above commandline):

[root@cloudera-master ~]# tail -5 /var/log/cloudera-scm-server/cloudera-scm-server.log 
2014-02-06 16:59:29,596  INFO [WebServerImpl:cmon.JobDetailGatekeeper@71] ActivityMonitor configured to allow job details for all jobs.
2014-02-06 16:59:29,597  INFO [WebServerImpl:cmon.JobDetailGatekeeper@71] ActivityMonitor configured to allow job details for all jobs.
2014-02-06 16:59:29,601  INFO [WebServerImpl:mortbay.log@67] jetty-6.1.26.cloudera.2
2014-02-06 16:59:29,605  INFO [WebServerImpl:mortbay.log@67] Started SelectChannelConnector@
2014-02-06 16:59:29,606  INFO [WebServerImpl:cmf.WebServerImpl@280] Started Jetty server.

Lets disable Linux Machine Firewall to see if it works:

First make sure you have to fiddle with your Firewall, below I am disabling the firewall in my Linux machine:

[root@cloudera-master ~]# /etc/init.d/iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[  OK  ]
[root@cloudera-master ~]# /etc/init.d/iptables stop
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]
[root@cloudera-master ~]# /etc/init.d/ip6tables save
ip6tables: Saving firewall rules to /etc/sysconfig/ip6table[  OK  ]
[root@cloudera-master ~]# /etc/init.d/ip6tables stop
ip6tables: Setting chains to policy ACCEPT: filter         [  OK  ]
ip6tables: Flushing firewall rules:                        [  OK  ]
ip6tables: Unloading modules:                              [  OK  ]
[root@cloudera-master ~]# chkconfig 
ip6tables           0:off     1:off     2:off     3:off     4:off     5:off     6:off
iptables            0:off     1:off     2:off     3:off     4:off     5:off     6:off

Once Firewall is stopped completely restart Cloudera Manager: 

If your machines are behind a firewall you can go ahead and disable the firewall on a machine which has Cloudera Manager running. If not please setup/open specific ports for Cloudera Manager to get it working.

[root@cloudera-master ~]# service –status-all | grep cloudera
cloudera-scm-server (pid  1082) is running…
/usr/bin/postgres “-D” “/var/lib/cloudera-scm-server-db/data”

[root@cloudera-master ~]# service cloudera-scm-server 
Usage: cloudera-scm-server {start|stop|restart|status}

[root@cloudera-master ~]# service cloudera-scm-server restart
Stopping cloudera-scm-server:                              [  OK  ]
Starting cloudera-scm-server:                              [  OK  ]

Note: that cloudera-scm-server is listed through chkconfig however the status shows OFF.

[root@cloudera-master ~]# chkconfig 
cloudera-scm-server     0:off     1:off     2:off     3:off     4:off     5:off     6:off
cloudera-scm-server-db     0:off     1:off     2:off     3:on     4:on     5:on     6:off

Once working and accessible the Cloudera Manager Login Page looks as below:



Screen Shot 2014-02-06 at 5.20.35 PM

Handling Hadoop Error "could only be replicated to 0 nodes, instead of 1" during copying data to HDFS or with mapreduce jobs

Sometimes copy files to HDFS or running a MapReduce jobs you might receive an error as below:

During file copy to HDFS the error and call stack look like as below:

File /platfora/uploads/test.xml could only be replicated to 0 nodes instead of minReplication (=1). There are 0 datanode(s) running and no node(s) are excluded in this operation

at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget(BlockManager.java:1339)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2198)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:501)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:299)
at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java:44954)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:453)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1002)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1751)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1747)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1408)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1745) 
UTC Timestamp: 11/20 04:14 amVersion: 2.5.4-IQT-build.73

During MapReduce job failure the error message and call stack look like as below:

DFSClient.java (line 2873) DataStreamer Exception: org.apache.hadoop.ipc.RemoteException: java.io.IOException: File ****/xyz.jar could only be replicated to 0 nodes, instead of 1

at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1569)
at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:698)
at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:573)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1393)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1389)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1132)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1387)

There could be various problems within datanode which could exhibit this issue such as:

  • Inconsistency in your datanodes
    • Restart your Hadoop cluster and see if this solves your problem.
  • Communication between datanodes and namenode
    • Network Issues
      • For example if you have Hadoop in EC2 instances and due to any security reason nodes can not talk, this problem may occur. You can fix the security by putting all nodes inside same EC2 security group to solve this problem.
    • Make sure that you can get datanode status from HDFS page or command line using command below:
      • $hadoop dfs-admin -report
  • Disk space full on datanode
    • What you can do is verify disk space availability in your system and make sure Hadoop  logs are not warning about disk space issue.
  • Busy or unresponsive datanode
    • Sometime datanodes are busy scanning block or working on a maintenance job initiated by namenode.
  • Negative block size configuration etc..
    • Please check the value of dfs.block.size in hdfs-site.xml and correct it per your Hadoop configuration

20TB Earth Science Dataset on AWS With NASA / NEX available for Public

AWS has been working with the NASA Earth Exchange (NEX) team to make it easier and more efficient for researchers to access and process earth science data. The goal is to make a number of important data sets accessible to a wider audience of full-time researchers, students, and citizen scientists. This important new project is called OpenNEX. Up until now, it has been logistically difficult for researchers to gain easy access to this data due to its dynamic nature and immense size (tens of terabytes). Limitations on download bandwidth, local storage, and on-premises processing power made in-house processing impractical.


Access Dataset: s3://nasanex/NEX-DCP30

Consult the detail page and the tech note to learn more about the provenance, format, structure, and attribution requirements.

NASA Earth Exchange (NEX):

The NASA Earth Exchange (NEX) Downscaled Climate Projections (NEX-DCP30) dataset is comprised of downscaled climate scenarios for the conterminous United States that are derived from the General Circulation Model (GCM) runs conducted under the Coupled Model Intercomparison Project Phase 5 (CMIP5) [Taylor et al. 2012] and across the four greenhouse gas emissions scenarios known as Representative Concentration Pathways (RCPs) [Meinshausen et al. 2011] developed for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). The dataset includes downscaled projections from 33 models, as well as ensemble statistics calculated for each RCP from all model runs available. The purpose of these datasets is to provide a set of high resolution, bias-corrected climate change projections that can be used to evaluate climate change impacts on processes that are sensitive to finer-scale climate gradients and the effects of local topography on climate conditions.

Each of the climate projections includes monthly averaged maximum temperature, minimum temperature, and precipitation for the periods from 1950 through 2005 (Retrospective Run) and from 2006 to 2099 (Prospective Run).

Website: NASA NEX


  • Short Name: NEX-DCP30
  • Version: 1
  • Format: netCDF4 classic
  • Spatial Coverage: CONUS
  • Temporal Coverage:
    • 1950 – 2005 historical or 2006 – 2099 RCP
  • Data Resolution:
    • Latitude Resolution: 30 arc second
    • Longitude Resolution: 30 arc second
    • Temporal Resolution: monthly
  • Data Size:
    • Total Dataset Size: 17 TB
    • Individual file size: 2 GB

Learn more about NEX – NASA Earth Exchange Downscaled Project

NEX Virtual Workshop: https://nex.nasa.gov/nex/projects/1328/


Top 20 Big Data Platfora and Analytics Startups with significant VC Funding

Top 20 Big Data and Analytics Startups with significant VC Funding



Funding in Million






Mu Sigma




Opera Solutions










ParAccel (Actian)























Top 20 Big Data


Keywords: Big Data, Data Analytics, Infographic, Hadoop,  BI