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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.

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question

rht.rajput_193125 avatar image
rht.rajput_193125 asked ·

Why is data not getting replicated to one of my nodes in the DS201 course VM?

As part of DS201, Replication exercise... Node3 was added as:

DC=west-side
RAC=hakuna-matata

Node1 and Node2 were already up and running.

Keyspace was created with following command:

CREATE KEYSPACE killrvideo WITH replication = {'class': 'NetworkTopologyStrategy','east-side': 1,'west-side': 1};

But execution resulted in a warning as follows:

Warning: schema version mismatch detected; check the schema versions of your nodes in system.local and system.peers.

Ignored this warning and went ahead and imported data into the table.

While trying to check for endpoints for each partition value, its only showing values on Node1 and Node2.. nothing on Node3.. why?

ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool getendpoints killrvideo videos_by_tag 'cassandra'
127.0.0.2
127.0.0.1
ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool getendpoints killrvideo videos_by_tag 'datastax'
127.0.0.1
127.0.0.2
ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool getendpoints killrvideo videos_by_tag 'action'
127.0.0.2
127.0.0.1
ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool getendpoints killrvideo videos_by_tag 'horror'
127.0.0.1
127.0.0.2
academyreplicationds201
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1 Answer

bettina.swynnerton avatar image
bettina.swynnerton answered ·

Hi

this is a related question to this post, where it looked like node3 is in a different datacenter due to its snitch configuration, so no data would have been replicated to this node with this replication strategy.

Once the snitches are aligned and the nodes are in the correct datacenters, this should get resolved.

I expect that this will also resolve the issue with the schema mismatch.

In any case, let us know how you get on with this.

Cheers!

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