Installing Cassandra¶

Downloading the Distribution¶

Binary distributions of Cassandra are available in the downloads section of the Cassandra website. Unless you have a specific need for features in a beta version, DataStax recommends the binary distribution of the latest stable version.

The rest of this document will refer to the directory where you unpack the distribution as $CASSANDRA_HOME. The subdirectories of $CASSANDRA_HOME are:

bin

Cassandra executables, including a startup script, the command-line client (CLI), and the nodetool utility for cluster management.

conf

Files for configuring Cassandra, including cassandra.yaml, an SH file containing important environment variables, and properties files for logging, authentication, and network topology.

interface

Contains cassandra.thrift (RPC client API) and Avro.

javadoc

Standard Javadoc API documentation for Cassandra.

lib

Contains external JARs and license documents.

Java Virtual Machine¶

A JVM is required to run Cassandra. DataStax recommends using the most recently released version of the Sun JVM. Versions earlier than 1.6.0_19 are specifically not recommended.

Data and Log Directories¶

By default, Cassandra uses the following directories for data and commitlog storage:

/var/lib/cassandra
/var/log/cassandra

Make sure that both of these directories exist and are writeable by Cassandra, either by changing their ownership or permissions. In Linux, this can be done as follows, where $USER is the user that will run Cassandra:

sudo mkdir /var/lib/cassandra
sudo mkdir /var/log/cassandra
sudo chown -R $USER:$GROUP /var/lib/cassandra
sudo chown -R $USER:$GROUP /var/log/cassandra

Setting the Initial Token¶

Before starting Cassandra, it is recommended to set the first node’s initial token value to zero. This simplifies load balancing as you later expand the cluster. To set the initial token value, edit $CASSANDRA_HOME/conf/cassandra.yaml and set 0 as the value for the parameter initial_token. If this is unset (the default), Cassandra picks a token number randomnly.

For multi-node clusters, initial tokens should be calculated and specified for each node. This procedure is described in Adding Nodes to a Cluster.

Installing JNA¶

Installing JNA (Java Native Access) on Linux platforms can improve Cassandra’s memory usage. With JNA installed and configured as described in this section, Linux does not swap out the JVM, and thus avoids related performance issues.

To install JNA with Cassandra

1. Download jna.jar from the JNA project site.
2. Add jna.jar to $CASSADRA_HOME/lib/ or otherwise place it on the classpath.
3. Edit the file /etc/security/limits.conf, adding the following entries for the user or group that runs Cassandra:

$USER soft memlock unlimited
$USER hard memlock unlimited

Starting Cassandra¶

Start Cassandra using the startup script in $CASSANDRA_HOME/bin.

cd $CASSANDRA_HOME
sh bin/cassandra -f

You can verify connectivity to your Cassandra instance with the nodetool command line utility in CASSANDRA_HOME/bin:

~$ nodetool -h localhost -p 8080 ring
Address     Status   State    Load         Owns      Range                                      Ring
127.0.0.1   Up       Normal   495 bytes    100%      95315431979199388464207182617231204396     |<--|

The Cassandra instance uses the following ports:

After Cassandra is installed successfully on a single node, you can continue to the steps for adding nodes to a Cassandra cluster.