Installation of Scylla on CentOS 7

Scylla on CentOS 7

Use these steps to install Scylla using Yum repositories on CentOS.

Prerequisites

• CentOS 7.2 or later, for the 64-bit x86_64 architecture.
• Yum package management application installed.
• ABRT conflict with Scylla coredump configuration. Remove it before installing Scylla: sudo yum remove -y abrt
• Root or sudo access to the system. The Scylla packages create a scylla user. When starting Scylla as a service, the service runs as this user.

Make sure that all the relevant ports are open.

Scylla uses the following ports

Port	Description	Protocol
9042	CQL (native_transport_port)	TCP
7000	Inter-node communication (RPC)	TCP
7001	SSL inter-node communication (RPC)	TCP
7199	JMX management	TCP
10000	Scylla REST API	TCP
9180	Prometheus API	TCP
9100	node_exporter (Optionally)	TCP
9160	Scylla client port (Thrift)	TCP

All ports above need to be open to external clients (CQL), external admin systems (JMX), and other nodes (RPC). REST API port can be kept closed for external incoming connections.

The JMX service, scylla-jmx, runs on port 7199. It is required in order to manage Scylla using nodetooland other Apache Cassandra-compatible utilities. The scylla-jmx process must be able to connect to port 10000 on localhost. The JMX service listens for incoming JMX connections on all network interfaces on the system.

For server configuration, see documentation on recommendations for high performance.

Scylla is supported on CentOS versions 7.2 or later. There is no support for CentOS version 6.x and earlier.

Procedure

$ sudo yum install epel-release

Install a repo file: Add the Scylla RPM repo to your system, check the RPM content

Scylla release 2.0 (recommended)
Repository for RHEL/CentOS 7 and above
sudo curl -o /etc/yum.repos.d/scylla.repo -L http://repositories.scylladb.com/scylla/repo/e2c2b99b2fbec823c5774e9138e7f7da/centos/scylladb-2.0.repo

More Versions

install packages

$ sudo yum install scylla

For a specific patch version, for example 1.7.1

$ sudo yum install scylla-1.7.1

Configure and run Scylla on CentOS

Configure Scylla

Configure the /etc/scylla/scylla.yaml file with the following parameters:

Item	Content
cluster_name	Name of the cluster, all the nodes in the cluster must have the same name
seeds	Seed nodes are used during startup to bootstrap the gossip process and join the cluster
listen_address	IP address that the Scylla use to connect to other Scylla nodes in the cluster
rpc_address	IP address of interface for client connections (Thrift, CQL)

More information regarding the scylla.yaml file.

scylla.yaml

scylla.yaml is equivalent to the Apache Cassandra cassandra.yaml configuration file, and it is compatible for relevant parameters. Below is a subset of scylla.yaml with parameters you are likely to update. For full list of parameters, look at the file itself.

# The name of the cluster. This is mainly used to prevent machines in
# one logical cluster from joining another.
cluster_name: 'Test Cluster'

# This defines the number of tokens randomly assigned to this node on the ring
# The more tokens, relative to other nodes, the larger the proportion of data
# that this node will store. You probably want all nodes to have the same number
# of tokens assuming they have equal hardware capability.
#
# If you already have a cluster with 1 token per node, and wish to migrate to
# multiple tokens per node, see http://wiki.apache.org/cassandra/Operations
num_tokens: 256

# Directory where Scylla should store data on disk.
data_file_directories:
    - /var/lib/scylla/data

# commit log.  when running on magnetic HDD, this should be a
# separate spindle than the data directories.
commitlog_directory: /var/lib/scylla/commitlog

# seed_provider class_name is saved for future use.
# seeds address are mandatory!
seed_provider:
    # Addresses of hosts that are deemed contact points.
    # Scylla nodes use this list of hosts to find each other and learn
    # the topology of the ring.  You must change this if you are running
    # multiple nodes!
    - class_name: org.apache.cassandra.locator.SimpleSeedProvider
      parameters:
          # seeds is actually a comma-delimited list of addresses.
          # Ex: "<ip1>,<ip2>,<ip3>"
          - seeds: "127.0.0.1"

# Address or interface to bind to and tell other Scylla nodes to connect to.
# You _must_ change this if you want multiple nodes to be able to communicate!
#
# Setting listen_address to 0.0.0.0 is always wrong.
listen_address: localhost

# Address to broadcast to other Scylla nodes
# Leaving this blank will set it to the same value as listen_address
# broadcast_address: 1.2.3.4

# port for the CQL native transport to listen for clients on
# For security reasons, you should not expose this port to the internet.  Firewall it if needed.
native_transport_port: 9042

# Uncomment to enable experimental features
# experimental: true

By default scylla.yaml is located at /etc/scylla/scylla.yaml

scylla.yaml required settings

The following configuration items must be set

Item	Content
cluster_name	Name of the cluster, all the nodes in the cluster must have the same name
seeds	Seed nodes are used during startup to bootstrap the gossip process and join the cluster
listen_address	IP address that the Scylla use to connect to other Scylla nodes in the cluster
rpc_address	IP address of interface for client connections (Thrift, CQL)

Scylla setup

Run the scylla_setup script to tune the system settings

sudo scylla_setup

This script invokes a set of scripts to configure several operating system settings, like setting RAID0 and XFS filesystem. It also runs a short (up to a few minutes) benchmark on your storage and generates the /etc/scylla.d/io.conf configuration file. When the file is ready, you can start Scylla (see below). Scylla will not run without XFS or io.conf file. To bypass this check, set Scylla to developer mode.

Run Scylla as a service (if not already running)

sudo systemctl start scylla-server

run nodetool

nodetool status

run cqlsh

cqlsh

Run cassandra-stress

cassandra-stress write -mode cql3 native

Monitoring

It is highly recommended to have a Scylla monitoring stack in place. For more on how to setup Scylla monitoring with Grafana here

Reference

Scylla servers set up using this method have the system configuration covered on System Configuration Guide already applied, by scripts included with the RPM packages. See the guide for a complete reference on settings used