After cassandra install via sudo apt install -y cassandra, cassandra is running, but I have not yet configured cassandra.yaml and cassandra-topology.properties. Once I configure them cassandra won't start because Cannot start node if snitch's data center (0) differs from previous data center (datacenter1)
Assuming that you don't care about the data stored, you can fix that by deleting everything in your data_file_directories. If you're not setting that, you'll find it at $CASSANDRA_HOME/data/data.
Basically, the cluster metadata gets written in the system keyspace, which uses the local replication strategy (system is unique on each node). At start time, Cassandra verifies the stored metadata vs. the config properties being passed. When you change something about the node, Cassandra will throw an error on specific properties like cluster_name, dc, rack (and possibly a few others) when they don't match what's on disk.
tl;dr;
You probably only need to delete only the data for the system keyspace.
But another option, would be to uncomment and set data_file_directories. Then the new node's system metadata would be written there, and the node would start.
Related
I have a cassandra 3.9 production cluster and I am trying to add a node to that cluster. However I am seeing this issue.
CASSANDRA-12813 NPE in auth for bootstrapping node
https://issues.apache.org/jira/browse/CASSANDRA-12813
Shy of upgrading my production cluster to 3.11 (which I may not be able to do immediately), is there a known workaround to this issue?
An undocumented (but works) way around this is to copy "system_auth" directory from another node and place it in the new node's data directory. Start Cassandra only after this step. This way setting up new auth table during bootstrap will be bypassed with the existing content. The content from the system_auth SSTables will not cause any harm, as its a copy of the users/roles belonging to tokens corresponding to that other node. Once copied repair, will take the responsibility of cleaning it up, if the tokens corresponding doesn't belong there.
Once the node has successfully been able to bootstrap, do a "nodetool repair" on system_auth keyspace and it would take care of the exact replica copies.
I had a cluster with 2 nodes (node 1 and node 2).
After decommissioning node 2 I wanted to use the server as a fresh Cassandra database for other purposes, but as soon as I restart this message appears:
org.apache.cassandra.exceptions.ConfigurationException: This node was
decommissioned and will not rejoin the ring unless
cassandra.override_decommission=true has been set, or all existing
data is removed and the node is bootstrapped again
So I removed all existing data.
But I don't want the node to be bootstrapped again (neither rejoin the previous ring) but to be a fresh new and pure Cassandra database to be used.
The old node is not on the seed list.
Cassandra version: 3.9
EDIT: I think I was missunderstood, sorry for that. After the decommission I want to have:
Db1: node 1
Db2: node 2
Two diferent databases with no correlation, totally separated. That's because we want to reuse the machine where node2 is hosted again to deploy a Cassandra DB in another enviroment.
Don't use override_decommission. That flag is only used for rejoining the same cluster.
You should remove all data files on the node (Cassandra will recreate system tables on start). Most importantly you need to change the seed in cassandra.yaml. I suspect that it is still the ip of node 1, so you need to change it to node 2 (itself).
Use option
cassandra.override_decommission: true
Use that option, cassandra.override_decommission=true. Also, be aware what is the definition of cluster_name is cassandra.yaml:
The name of the cluster. This setting prevents nodes in one logical
cluster from joining another. All nodes in a cluster must have the
same value.
So, to be sure, also use another value for cluster_name option in cassandra.yaml.
Try these steps:
run in cqlsh: UPDATE system.local SET cluster_name = 'new_name'
where key='local';
nodetool flush in order to persist the data
nodetool decommission
stop node
change name in cassandra.yaml
clean node sudo rm -rf /var/lib/cassandra/* /var/log/cassandra/* but I would just move those file in some other place until you get the state that you want
start node
Please check 1, 2
We are running 6 node cluster with:
HADOOP_ENABLED=0
SOLR_ENABLED=0
SPARK_ENABLED=0
CFS_ENABLED=0
Now, we would like to add Spark to all of them. It seems like "adding" is not the right term because this would not fail. Anyways, the steps we've done:
1. drained one of the nodes
2. changed /etc/default/dse to SPARK_ENABLED=1 and HADOOP_ENABLED=0
3. sudo service dse restart
And got the following in the log:
ERROR [main] 2016-05-17 11:51:12,739 CassandraDaemon.java:294 - Fatal exception during initialization
org.apache.cassandra.exceptions.ConfigurationException: Cannot start node if snitch's data center (Analytics) differs from previous data center (Cassandra). Please fix the snitch configuration, decommission and rebootstrap this node or use the flag -Dcassandra.ignore_dc=true.
There are two related questions that have been already answered:
Unable to start solr aspect of DSE search
Two node DSE spark cluster error setting up second node. Why?
Unfortunately, clearing the data on the node is not an option - why would I do that? I need the data to be intact.
Using "-Dcassandra.ignore_rack=true -Dcassandra.ignore_dc=true" is a bit scary in production. I don't understand why DSE wants to create another DC and why can't it just use the existing one?
I know that according to datastax's doc one should partition the load using different DC for different workloads. In our case we just want to run SPARK jobs on the same nodes that Cassandra is running using the same DC.
Is that possible?
Thanks!
The other answers are correct. The issue here is trying to warn you that you have previously identified this node as being in another DC. This means that it probably doesn't have the right data for any key-spaces with Network Topology Strategy. For example if you had a NTS keyspace which had only one replica in "Cassandra" and changed the DC to "Analytics" you could inadvertently lose all of the data.
This warning and the accompanying flag are telling you that you are doing something that you should not be doing in a production cluster.
The real solution to this is to explicitly name your dc's using GossipingFileSnitch and not rely on SimpleSnitch which names based on the DSE workload.
In this case, switch to GPFS and set the DC name to Cassandra.
I installed apache cassandra on my local system for testing purpose. With 1 system (1 node) i was able to read/write and query in the database. I added another node and created a cluster. Now the data that I write on my system is replicated on other node and vice versa, but the data which was present on my system earlier to the addition of new node is not replicated. Though the Keyspaces and Tables are present on new node but they are empty. Did I do something wrong while adding the new node to the cluster?
My best guess is that you have auto_bootstrap turned off (it is ON by default). From the documentation:
auto_bootstrap
(Default: true ) This setting has been removed from default configuration. It makes new (non-seed) nodes automatically migrate the right data to themselves. When initializing a fresh cluster with no data, add auto_bootstrap: false.
The easiest way to fix this is to run a repair on the node which will ensure that it gets any data it's missing.
http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_repair_nodes_c.html
Simply run this on new node if the data on it is not up-to-date.
Run $CASSANDRA_HOME/bin/nodetool rebuild
Login as cqlsh and verify that new node has received the data.
Also look into below -
http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_add_dc_to_cluster_t.html
If you have correct seeds and replication settings. But still the data is not getting replicated to new data center. Please perform nodetool repair with -full option will replicate data to the new datacenter node.
I am trying to connect Apache Cassandra nodes into a ring. They are not Datastax versions, but Cassandra 1.2.8 from the Apache website. When trying to add one as the seed of the other I get following exception:
Unable to find compaction strategy class 'com.datastax.bdp.hadoop.cfs.compaction.CFSCompactionStrategy'
Before that I change the "listen_address" and "rpc_address" to local IP address of each node. Next step I add one IP as a seed to another node. The nodes start up, an exception is printed but both nodes run fine until restart. After restarting either node the exception is printed and nodes do not run.
This is very strange - I do not have any DSE components.
Did you previously use any DSE components? If you did and are using the same data directory on any of your nodes, it may find old column families that were created with this compaction strategy. If you have no data you want in the data directories on all your nodes, you should clear them by stopping all nodes, deleting the directories, then starting the nodes.
Or if you have any DSE nodes still up, they may be joining the new cluster and propagating their schema, so creating column families with this compaction strategy. You can find out by looking in the logs and seeing which nodes try to connect. If any aren't from your 1.2.8 ring then this is probably the cause.
That error means you either had a DSE Analytics node in your ring at some point, or you restored your schema from someplace that had an Analytics node.
I would check if you have the folder /etc/dse/ on your VM, that would mean DSE was installed there.
To just wipe the node and start from scratch schema wise, you can stop the node, remove the /system/schema_* folders, then start the node. When it starts it will have no schema. Re-create any keyspaces/column families you had before, and they will get read from disk.