# Create a ScyllaDB Cluster - Single Datacenter (DC) ## Prerequisites * Make sure that all the [ports](https://docs.scylladb.com/manual/master/operating-scylla/admin.md#cqlsh-networking) are open. * Obtain the IP addresses of all nodes that have been created for the cluster. * Choose one of the nodes to be a seed node. You’ll need to provide the IP of that node using the seeds parameter in the scylla.yaml configuration file on each node. * Select a unique name as `cluster_name` for the cluster (identical for all the nodes in the cluster). * Choose which [snitch](https://docs.scylladb.com/manual/master/faq.md#faq-snitch-strategy) to use (identical for all the nodes in the cluster). For a production system, it is recommended to use a DC-aware snitch, which can support the `NetworkTopologyStrategy` [replication strategy](https://docs.scylladb.com/manual/master/cql/ddl.md#create-keyspace-statement) for your keyspaces. ## Procedure 1. Install ScyllaDB on the nodes you want to add to the cluster. See [Getting Started](https://docs.scylladb.com/manual/master/getting-started/index.md) for further instructions. Follow the ScyllaDB install procedure up to `scylla.yaml` configuration phase. In case the node starts during the process, follow [these instructions](https://docs.scylladb.com/manual/master/operating-scylla/procedures/cluster-management/clear-data.md) 2. On each node, edit the `scylla.yaml` file to configure the parameters listed below. The file can be found under `/etc/scylla/`. - **cluster_name** - Set the selected cluster_name - **seeds** - Specify the IP of the node you chose to be a seed node. New nodes will use the IP of this seed node to connect to the cluster and learn the cluster topology and state. - **listen_address** - IP address that ScyllaDB used to connect to other ScyllaDB nodes in the cluster - **endpoint_snitch** - Set the selected snitch - **rpc_address** - Address for CQL client connection 3. This step needs to be done **only** if you are using the **GossipingPropertyFileSnitch**. If not, skip this step. In the `cassandra-rackdc.properties` file, edit the parameters listed below. The file can be found under `/etc/scylla/` - **dc** - Set the datacenter name - **rack** - Set the rack name For example: ```shell # cassandra-rackdc.properties # # The lines may include white spaces at the beginning and the end. # The rack and data center names may also include white spaces. # All trailing and leading white spaces will be trimmed. # dc=thedatacentername rack=therackname # prefer_local= # dc_suffix= ``` 1. Start the nodes. Supported OS ```shell sudo systemctl start scylla-server ``` Docker ```shell docker exec -it some-scylla supervisorctl start scylla ``` (with *some-scylla* container already running) 5. Verify that the nodes have been added to the cluster using `nodetool status`. ## Example This example shows how to install and configure a three-node cluster using GossipingPropertyFileSnitch as the endpoint_snitch, each node on a different rack. 1. Install three ScyllaDB nodes; the IPs are: ```shell 192.168.1.201 (seed) 192.168.1.202 192.168.1.203 ``` 1. In each ScyllaDB node, edit the `scylla.yaml` file **192.168.1.201** ```shell cluster_name: 'Scylla_cluster_demo' seeds: "192.168.1.201" endpoint_snitch: GossipingPropertyFileSnitch rpc_address: "192.168.1.201" listen_address: "192.168.1.201" ``` **192.168.1.202** ```shell cluster_name: 'Scylla_cluster_demo' seeds: "192.168.1.201" endpoint_snitch: GossipingPropertyFileSnitch rpc_address: "192.168.1.202" listen_address: "192.168.1.202" ``` **192.168.1.203** ```shell cluster_name: 'Scylla_cluster_demo' seeds: "192.168.1.201" endpoint_snitch: GossipingPropertyFileSnitch rpc_address: "192.168.1.203" listen_address: "192.168.1.203" ``` 1. This step only needs to be done if you’re using **GossipingPropertyFileSnitch**. In each ScyllaDB node, edit the `cassandra-rackdc.properties` file. **192.168.1.201** ```shell # cassandra-rackdc.properties # # The lines may include white spaces at the beginning and the end. # The rack and data center names may also include white spaces. # All trailing and leading white spaces will be trimmed. # dc=datacenter1 rack=rack43 # prefer_local= # dc_suffix= ``` **192.168.1.202** ```shell # cassandra-rackdc.properties # # The lines may include white spaces at the beginning and the end. # The rack and data center names may also include white spaces. # All trailing and leading white spaces will be trimmed. # dc=datacenter1 rack=rack44 # prefer_local= # dc_suffix= ``` **192.168.1.203** ```shell # cassandra-rackdc.properties # # The lines may include white spaces at the beginning and the end. # The rack and data center names may also include white spaces. # All trailing and leading white spaces will be trimmed. # dc=datacenter1 rack=rack45 # prefer_local= # dc_suffix= ``` 1. Start the nodes. Supported OS ```shell sudo systemctl start scylla-server ``` Docker ```shell docker exec -it some-scylla supervisorctl start scylla ``` (with *some-scylla* container already running) 1. Verify that the nodes have been added to the cluster by using the `nodetool status` command. ```shell Datacenter: datacenter1 Status=Up/Down State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns (effective) Host ID Rack UN 192.168.1.201 112.82 KB 256 32.7% 8d5ed9f4-7764-4dbd-bad8-43fddce94b7c 43 UN 192.168.1.202 91.11 KB 256 32.9% 125ed9f4-7777-1dbn-mac8-43fddce9123e 44 UN 192.168.1.203 124.42 KB 256 32.6% 675ed9f4-6564-6dbd-ca08-43fddce952de 45 ```