Temporarily change multi node to single node

1
votes

I have configured cassandra 3.0.9 on 3 nodes but I have to use only 1 node for sometime. I have disconnected other 2 nodes from network also removed the entries of both the nodes from Cassandra.yaml, rackdc and topology files.

When I check node tool status it shows me both the down nodes. When I try to execute any query on cqlsh it gives me below error:

Blockquote OperationTimedOut: errors={'127.0.0.1': 'Request timed out while waiting for schema agreement. See Session.execute_async and Cluster.max_schema_agreement_wait.'}, last_host=127.0.0.1

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

How I can resolve this?

1
cassandracassandra-3.0

1 Answers

2
votes

That's not how you remove a node from a Cassandra cluster. In fact, what you're doing is quite dangerous. Typically, you'd use nodetool decommission. If your other two nodes are still intact and just offline, I suggest bringing them back online temporarily and let decommission do its thing.

I'm going to also throw this out there - it's possible you're missing a good portion of your data with the steps you did above unless all keyspaces had RF=3. Cassandra distributes data evenly between the nodes in a respective DC. The decommission step I mention above redistributes the data.

Now if you don't have the other 2 nodes to run a nodetool decommission, you may have to remove the node with nodetool removenode and in the worst case, nodetool assassinate.

Check these docs for reference and the full steps to removing a node: https://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsAddingRemovingNodeTOC.html