bin

This directory contains the startup scripts to launch the Cassandra server, the cqlsh prompt, and utility tools such as nodetool.

conf

This directory is the home of configuration files, including cassandra.yaml.

lib

This directory is Cassandra's Java dependency folder.

pylib

This directory contains Python libraries for cqlsh.

tools

Stress testing tools like cassandra-stress and other tools for example, sstable2json: which could be used to convert SSTables to JSON for debugging purposes. An SSTable or Sorted String Table is an immutable data file in disk, created for each Column Family. There could be zero or more SSTable per Column Family in every node of Cassandra cluster.

data

The Cassandra data directory will be created as soon as you start populating your Cassandra server. Its location is configured using the data_file_directories in the cassandra.yaml option.

logs

This is the default log directory. In older versions, it was /var/log/Cassandra.

/var/lib/cassandra

This is the data directory.

/var/log/cassandra/

This is the log directory.

/var/run/Cassandra

This is the runtime file location, for example, the PID file.

/usr/share/Cassandra

This is the home of the include file cassandra-in.sh, which is used to set environment variables, such as CASSANDRA_HOME, CLASSPATH, and so on for Cassandra.

/usr/share/cassandra/lib

This is Cassandra's Java dependency folder; JAR files are placed here.

/usr/bin

This is the home of tools and utilities such as cqlsh, nodetool, and cassandra-stress.

/etc/cassandra

This is the home of the configuration.

/etc/init.d/

This contains the Cassandra startup scripts.

/etc/security/limits.d/

This is the file defining Cassandra user limits.