Create a Scylla Cluster on EC2 (Single or Multi Data Center)

The easiest way to run a Scylla cluster on EC2 is using CentOS base Scylla AMI. However, if you wish to use a different OS or your own AMI (Amazon Machine Image), or setup a multi DC Scylla cluster, you will need to configure Scylla cluster on your own. This page guides you through this process.

Scylla cluster on EC2 can deployed as a single-DC or a multi-DC. The table below described how to configure scylla.yaml parameters for each node in your cluster for each case.

Best practice is to use each EC2 region as a Scylla DC. In such a case, nodes communicating using Internal (private) IPs inside the region, and using External (Public) IPs between regions (Data Centers)

For further information on AWS instance addressing

EC2 Configuration Table

Parameter Single DC Multi DC
seeds Internal IP address External IP address
listen_address Internal IP address Internal IP address
rpc_address Internal IP address Internal IP address
broadcast_address Internal IP address External IP address
broadcast_rpc_address Internal IP address External IP address
endpoint_snitch Ec2Snitch Ec2MultiRegionSnitch

Prerequisites

  • EC2 instance with ssh access.
  • Make sure that all the relevant ports are open in your EC2 Security Group.
  • Select a unique name as cluster_name for the cluster (identical for all the nodes in the cluster).
  • Decide which nodes will be the seed nodes (It is recommended to define more than one node as a seed node per data-center).

Procedure

These steps need to be done for each of the nodes in the new cluster.

1. Install Scylla on a node, see Getting Started for further instructions. Follow the Scylla install procedure up to scylla.yaml configuration phase.

In case that Scylla service is already running, for example, if you are using Scylla AMI, stop it before moving to the next step by using these instructions

2. In the scylla.yaml file edit the parameters listed below, the file can be found under /etc/scylla/ consult the table above how to configure your cluster.

  • cluster_name - Set the selected cluster_name
  • seeds - Set the selected seed nodes
  • listen_address - IP address that Scylla used to connect to other Scylla nodes in the cluster
  • auto_bootstrap - By default, this parameter is set to true, it allow new nodes to migrate data to themselves automatically. If using Scylla AMI add --bootstrap to the user settings when creating a node
  • endpoint_snitch - Set the selected snitch
  • rpc_address - Address for client connection (Thrift, CQL)
  • broadcast_address - The IP address a node tells other nodes in the cluster to contact it by
  • broadcast_rpc_address - Default: unset, RPC address to broadcast to drivers and other Scylla nodes. This cannot be set to 0.0.0.0. If left blank, this will be set to the value of rpc_address. If rpc_address is set to 0.0.0.0, broadcast_rpc_address must be configured

3. After you have installed and configured Scylla and edit scylla.yaml file on all the nodes, start the seed nodes one at a time, and then start the rest of the nodes in your cluster using sudo systemctl start scylla-server

4. Verify that the node added to the cluster using. nodetool status

EC2 snitchs Default DC and Rack Names, and how to Override DC Names

EC2snitch and Ec2MultiRegionSnitch give each DC and rack default names, the region name defined as datacenter name and availability zones are defined as racks within a datacenter. EC2snitch and Ec2MultiRegionSnitch give each DC and rack default names, the region name defined as datacenter name and availability zones are defined as racks within a datacenter, the rack names can’t be changed.

For example:

A node in the us-east-1 region, us-east is the data center name and 1 is the rack location.

To change the DC names do the following:

Edit the cassandra-rackdc.properties file with the prefered data-center name. The file can be found under /etc/scylla/

The dc_suffix defines a suffix added to the data-center name as described below.

For example:

Region us-east

dc_suffix=_1_scylla will be us-east_1_scylla

Or

Region us-west

dc_suffix=_1_scylla will be us-west_1_scylla