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For a simple environment such as called out in Build a Virtualized 5-Node Hadoop 2.0 Cluster, first create a new linux user and set a password for the new account.

useradd -m -s /bin/bash theNEWusername
passwd theNEWusername

Then create a HDFS home directory for this new user.

su hdfs
hdfs dfs -mkdir /user/theNEWusername
hdfs dfs -chown theNEWusername /user/theNEWusername

Hortonworks Sandbox

http://127.0.0.1:8888/  (HUE: hue/1111  and   AMBARI: admin/admin)

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scp -P 2222 example.jar mruser@127.0.0.1:/home/mruser/mrJars (password is "Sprint2000" for linux user and "hadoop" for one created in hue)

Networking & VirtualBox

if you make changes to /etc/sysconfig/network-scripts/ifcfg-eth0, then make sure you rm /etc/udev/rules.d/70-persistent-net.rules

HDP File Locations

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Binaries: /usr/lib/SERVICENAME

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Logs: /var/log/SERVICENAME

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Benchmarking & Performance/Scalability Testing

• Benchmarking and Stress Testing a Hadoop Cluster
• Teragen & Terasort on HDP (the argument is how many lines of 100 bytes you want - 10,000,000,000 would net you 1TB of data)
  • HDP 1.3.2 (correctly identified that 100000000 would give you 10GB)
  • HDP 2.0.9.0 (incorrectly identifies that 10000 would give you 10GB, but that is really only 1MB)

Repo Help

• How to prepare your CentOS6 to install HDP 2.x

Apache Ambari

• Examples of Ambari REST API
  • https://community.cloudera.com/t5/Support-Questions/how-to-capture-all-ambari-services-components-status-by-API/td-p/179701
  • https://community.cloudera.com/t5/Community-Articles/Popular-Ambari-REST-API-Commands/ta-p/249359
• Ambari Shell for CLI commands; https://cwiki.apache.org/confluence/display/AMBARI/Ambari+Shell

Other Stuff

• Script to iterate down a dir tree and copy everything into HDFS; http://one-line-it.blogspot.com/2013/05/hadoop-copy-directly-to-hdfs-from.html
• How to set the number of mappers and reducers of Hadoop in command line
• Details on HDFS Balancer command; http://www.swiss-scalability.com/2013/08/hadoop-hdfs-balancer-explained.html
• Oracle JDK 7 Archive Download Page
• SAP HANA and HDP Integration; http://hortonworks.com/wp-content/uploads/2013/09/Demo-Tutorial-Leveraging_SAP_HANA__HDP_Jan_2014.pdf
• Creating & registering custom Ambari alerts; https://community.hortonworks.com/articles/38149/how-to-create-and-register-custom-ambari-alerts.html
• Managing Hadoop DR with distcp and snapshots; https://community.cloudera.com/t5/Community-Articles/Managing-Hadoop-DR-with-distcp-and-snapshots/ta-p/248362

YARN

Kill a hadoop job:

yarn application -kill $ApplicationId

You can get a list of all ApplicationId's doing:

yarn application -list

Random Notes

dfs.datanode.max.transfer.threads - default is 1024, but bump to >= 4096 or >= 16K for HBase