DataStax Academy FAQ

DataStax Academy migrated to a new learning management system (LMS) in July 2020. We are also moving to a new Cassandra Certification process so there are changes to exam bookings, voucher system and issuing of certificates.

Check out the Academy FAQ pages for answers to your questions:


question

zoyan173_192891 avatar image
zoyan173_192891 asked ·

How do I run cassandra-stress on Academy VM DS201?

When running the command from step 8), it throw following exception, previous steps all passed without any issue:

java.lang.RuntimeException: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: localhost/0:0:0:0:0:0:0:1:9041 (com.datastax.driver.core.exceptions.TransportException: [localhost/0:0:0:0:0:0:0:1:9041] Cannot connect), localhost/127.0.0.1:9041 (com.datastax.driver.core.exceptions.TransportException: [localhost/127.0.0.1:9041] Cannot connect))
at org.apache.cassandra.stress.settings.StressSettings.getJavaDriverClient(StressSettings.java:148)
at org.apache.cassandra.stress.settings.StressSettings.getJavaDriverClient(StressSettings.java:116)
at org.apache.cassandra.stress.settings.SettingsSchema.createKeySpaces(SettingsSchema.java:66)
at org.apache.cassandra.stress.settings.StressSettings.maybeCreateKeyspaces(StressSettings.java:156)
at org.apache.cassandra.stress.StressAction.run(StressAction.java:56)
at org.apache.cassandra.stress.Stress.run(Stress.java:143)
at org.apache.cassandra.stress.Stress.main(Stress.java:62)
Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: localhost/0:0:0:0:0:0:0:1:9041 (com.datastax.driver.core.exceptions.TransportException: [localhost/0:0:0:0:0:0:0:1:9041] Cannot connect), localhost/127.0.0.1:9041 (com.datastax.driver.core.exceptions.TransportException: [localhost/127.0.0.1:9041] Cannot connect))
at com.datastax.driver.core.ControlConnection.reconnectInternal(ControlConnection.java:237)
at com.datastax.driver.core.ControlConnection.connect(ControlConnection.java:84)
at com.datastax.driver.core.Cluster$Manager.negotiateProtocolVersionAndConnect(Cluster.java:1622)
at com.datastax.driver.core.Cluster$Manager.init(Cluster.java:1540)
at com.datastax.driver.core.Cluster.getMetadata(Cluster.java:402)
at org.apache.cassandra.stress.util.JavaDriverClient.connect(JavaDriverClient.java:177)
at org.apache.cassandra.stress.settings.StressSettings.getJavaDriverClient(StressSettings.java:139)
... 6 more


academyds201
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1 Answer

bettina.swynnerton avatar image
bettina.swynnerton answered ·

Hi @zoyan173_192891,

try specifying the node to connect to explicitly:

/home/ubuntu/node/resources/cassandra/tools/bin/cassandra-stress
   write no-warmup n=250000 -node 127.0.0.1 -port native=9041 -rate threads=1

From the error trace it seems that it doesn't pick the right IP address in this setup.

I quickly tested this on my VM, and the above command launched cassandra-stress correctly.

Let us know how you get on.

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Tried with above command and still fail, but this remind me the issue of IP and Port, so finally I found it is on different port. It is just so confusing, for same IP for example here it is 127.0.0.1, the port can be different. In my case, it is 9042, NOT 9041. Once I put correct port, it is working now. Really wondering how this assigned at the back ??

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Happy to hear that it is working now.

And regarding the ports, it is a special situation with the VM, as we want to create several nodes on the same physical machine, and we only have the localhost address available. This is not how you would install a cluster for real, it is a workaround to help with the multi node exercises. It is a challenge to teach distributed system concepts on a single VM :)

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