Got a four node apache cassandra cluster (2.1) with DataStax opscenter 5.0.1 running. Everything's running smoothly...I can restart nodes from opscenter. However, if I try to run a repair on a node from the Opscenter UI, I get the following:
"Error during repair on [hostname]: java.lang.NullPointerException:"
I can ssh into the node and run nodetool repair without problems.
Any idea what the problem might be?
Opscenter 5.0 doesn’t support managing Cassandra 2.1 clusters yet, but that’ll change after 5.1 gets released.
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Whenever I am restarting my any Cassandra node in my cluster after few minutes other nodes are showing down, sometimes other nodes also hanging. We need to restart other nodes to up the services.
During restart cluster seems unstable and one after other showing stress and DN status however JVM and nodetool services are running fine but when we are describing the cluster it is showing unreachable.
We don't have much traffic and load in our environment. Can you please give me any suggestion.
Cassandra version is 3.11.2
Do you see any error/warning in your system.log after the restart of the node?
We have currently using DSE 4.8 and 5.12. we want to migrate to apache cassandra .since we don't use spark or search thought save some bucks moving to apache. can this be achieved without down time. i see sstableloader works other way. can any one share me the steps to follow to migrate from dse to apache cassandra. something like this from dse to apache.
https://support.datastax.com/hc/en-us/articles/204226209-Clarification-for-the-use-of-SSTABLELOADER
Figure out what version of Apache Cassandra is being run by DSE. Based on the DSE documentation DSE 4.8.14 is using Apache Cassandra 2.1 and DSE 5.1 is using Apache Cassandra 3.11
Simplest way to do this is to build another DC (Logical DC per Cassandra) and add it to the existing cluster.
As usual, with a "Nodetool Rebuild {from-old-DC}" on to the new DC nodes, let Cassandra take care of streaming data to the new Apache Cassandra nodes naturally.
Once data streaming is completed, based on the LoadBalancingPolicy being used by applications, switch their local_dc to DC2 (the new DC). Once the new DC starts taking traffic, shutdown nodes in old DC say DC1 one by one.
alter keyspace dse_system and dse_security not using everywhere
on non-seed nodes, cleanup cassandra data directory
turn on replace in cassandra-env.sh
start instance
monitoring streaming process using command 'nodetool netstats|grep Receiving'
change seeds node definition and rolling restart before finally migrate previous seeds nodes.
I want to run repair/compact operation from 1 Cassandra cluster node instead of scheduling it from all nodes in a cluster.
I am using cassandra 3 version.
"nodetool -h **NODEIP** repair keyspace" is not working if I specify other node in the cluster. This command only works for the local node which I run this command. Please suggest a way to run repair/compaction for all nodes by running from one node in a cluster.
Thanks
By default JMX security is disabled and accessible only from localhost, as nodetool uses JMX to communicate with Cassandra, nodetool will only work on the local node unless JMX security is enabled.
See this Datastax page on how to enable JMX authentication.
I know datastax-agent is used to show to data in opscenter. But if we aren't using it, can we stop the datastax-agent process? Does it have any other use?
We are using Cassandra 3.7
The datastax-agent is only used for OpsCenter. Its fine to stop the process. Just be aware that you might see errors in OpsCenter for that node, if you are still using it.
OpsCenter is not compatible with open source Cassandra 3.x and there should not be a running datastax-agent service in 3.7. OpsCenter 6.0 only works with DSE Cassandra.
I am in process of upgrading Cassandra from 2.0.9 to 2.1.14. In the upgrade instructions, it says we should run nodetool upgradesstables after the upgrade process.
I have 12 nodes in my cluster. When I start the upgrade process on a node, do I need to run nodetool upgradesstables on that node after starting it with the new version? Or after all nodes have been upgraded to the new version?
You'll want to do it after all nodes have been upgraded.
nodetool upgradesstables can take a while to complete (depending on the size of your data). But the good news is that Cassandra 2.1 can read 2.0 sstables, so you can run it at your leisure (good idea to do so during off-hours).
That being said, make sure it runs to completion on all nodes, as your next upgrade (2.2) depends on it (2.2 cannot read 2.0 sstables).