Steps to add nodes when using virtual nodes.
Virtual nodes (vnodes) greatly simplify adding nodes to an existing cluster:
- Calculating tokens and assigning them to each node is no longer required.
- Rebalancing a cluster is no longer necessary because a node joining the cluster
assumes responsibility for an even portion of the data.
For a detailed explanation about how this works, see Virtual nodes.
Procedure
-
Install Cassandra on the new nodes, but do not start Cassandra.
If you used a packaged install, Cassandra starts automatically and you must
and stop the
node and clear the data.
-
Set the following properties in the cassandra.yaml and
cassandra-topology.properties configuration
files:
- auto_bootstrap
- If this option has been set to false, you must set it to
true. This option is not listed in the default
cassandra.yaml file and is set to
true by default.
- cluster_name -
the name of the cluster the new node is joining.
- listen_address/broadcast_address
- the IP address or host name that other Cassandra nodes use to connect to
the new node.
- endpoint_snitch -the
snitch Cassandra uses for locating nodes and routing requests.
- num_tokens -the
number of vnodes to assign to the node. If the hardware capabilities vary
among the nodes in your cluster, you can assign a proportional number of
vnodes to the larger machines.
- seed_provider -
the - seeds list in this setting determines which nodes the
new node should contact to learn about the cluster and establish the gossip
process. Change other non-default settings you have made to your existing
cluster in the cassandra.yaml file and
cassandra-topology.properties files. Use the
diff command to find and merge (by head) any
differences between existing and new nodes.
-
Start Cassandra on each new node. Allow two minutes between node
initializations. You can monitor the startup and data streaming process using
nodetool
netstats.
-
After all new nodes are running, run nodetool cleanup on each of
the previously existing nodes to remove the keys no longer belonging to those
nodes. Wait for cleanup to complete on one node before doing the next.
Cleanup may be safely postponed for low-usage hours.
