What Should You Do when the Apache Mesos Web UI Keeps Refreshing and Sending a Pop-up “Failed to connect to …:5050”?

Problem scenario
You deployed Apache Mesos. The web UI is having problems. You see the error “Failed to connect to x.x.x.x:5050.” What should you do?


  1. Go to the back-end of the Apache Mesos server. Run this command: sudo systemctl stop mesos-master
  2. sudo find / -name mesos-master.sh
  3. Change directory into the parent of the “bin” directory that houses the mesos-master.sh as found above.

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How Do You Install Sqoop?

Problem scenario
You have Hadoop installed on a Linux machine. You want to install Apache Sqoop. What do you do?

Verify one of these commands work:
hadoop dfs -ls
hdfs dfs ls
# If you need assistance installing Hadoop, see this posting.

Download the installation media here: http://www.apache.org/dyn/closer.cgi/sqoop/

There are other sources.

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How Do You Troubleshoot the Installation of Apache Accumulo on Linux?

Problem scenario
You are trying to install open source Accumulo on Linux. You have two GB of swap space. You have installed Java, Hadoop, and Zookeeper. You have run the bootstrap_config.sh script for Accumulo 1.9.2.

You run this (and expected it to work): /bin/accumulo-1.9.2/bin/accumulo init

But you get this error:

OpenJDK 64-Bit Server VM warning: If the number of processors is expected to increase from one,  » Read more..

How Do You Set Up a Multi-Node Cluster of Zookeeper?

Problem scenario
You want to set up Zookeeper with three nodes in AWS. What do you do?

1. Install Zookeeper on each of the servers. If you need assistance with this, see this posting.

2. Modify the zoo.cfg file on each of the servers. Add stanzas like these but substitute foobarX.amazonaws.com with the Public DNS name of each server:



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How Do You Troubleshoot HBase Commands That Hang?

Problem scenarios
One of the following apply to you.

Problem #1
You run an HBase command but it hangs indefinitely, and there is no error. What could be the problem?

Problem #2
You run an HBase command but you see this:
“ERROR: KeeperErrorCode = ConnectionLoss for /hbase/master”

Has Zookeeper been started?

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How Do You Troubleshoot Cassandra when It Hangs on the Message “ColumnFamilyStore.java Initializing”?

Problem scenario
You start Cassandra with this command: ./bin/cassandra
You see one of the following messages:

INFO [MigrationStage:1] 2018-04-06 19:01:07,144 ColumnFamilyStore.java:391 – Initializing system_auth.resource_role_permissons_index
INFO [MigrationStage:1] 2018-04-06 19:01:07,163 ColumnFamilyStore.java:391 – Initializing system_auth.role_members

No progress is happening. What should you do?

Possible Solution #1. Try rebooting the server. This could help the problem.

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What Do You Do when Cassandra Stalls on “Initializing IndexInfo”?

Problem scenario
When you start Cassandra you see a message such as this:

INFO [main] 2018-02-03 08:45:55,257 ColumnFamilyStore.java:389 – Initializing system.IndexInfo

What should you do?

Possible Solution #1
Try rebooting the server. This could help the problem.

Possible Solution #2
This next one is merely a workaround. It is not a best practice.

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A List of Books on Message Queuing Solutions: ActiveMQ, AMQP, WebSphere and ZeroMQ

This is a list of books focusing on message queuing solutions other than RabbitMQ.  For RabbitMQ, see this link.

ActiveMQ in Action by Bruce Snyder, Dejan Bosanac and Rob Davies
Code Connected Volume 1: Learning ZeroMQ by Pieter Hintjens
Programming WebSphere MQ with JAVA by Kunal Jaggi
ZeroMQ: Messaging for Many Applications  by Faruk Akgul
ZeroMQ: Messaging for Many Applications by Pieter Hintjens

How Do You Install Apache Rya on Any Distribution of Linux?

Problem Scenario
You want to install Apache Rya on Linux. What do you do?


i. You need a server with at least 5 GB of total memory. You can create swap space with this posting. (Remember that 1 GB of RAM and 2 GB of swap space will be insufficient for installing Rya.)

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How Do You Troubleshoot This Error “org.apache.bsf.BSFManager or javax.script.ScriptEngineManager”?

Problem scenario
You are running Ant and you get this error:

“Unable to load a script engine manager (org.apache.bsf.BSFManager or javax.script.ScriptEngineManager”

What should you do?


Uninstall Ant (e.g., sudo apt-get -y remove ant). Install the latest version of Ant. If you need directions, see this posting as it works on any distribution of Linux.

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