Volumes Overview

Volume types and purposes

Data in an Exasol database is stored on volumes that are assigned to storage disks.

Exasol databases have two volume types with different purposes: data volumes and archive volumes. A typical Exasol setup contains at least one data volume and one archive volume.

Volume purpose	Volume type	Description
Storing persistent data of a database	Data	The size parameter of the volume determines the maximum size of the volume. The actual size of the volume increases or decreases depending on the data stored. Persistent data volumes usually have redundancy level 2.
Storing compressed backups of a database	Archive	Backups are stored in remote archive volumes on external user-managed services such as Amazon S3 or an ftp server. The size parameter of the volume determines the maximum size of the volume. Archive volumes usually have redundancy level 2.
Storing temporary data	Data	Temporary data volumes are automatically created when a database instance is started, and automatically deleted when the database instance is stopped. The initial size when the volume is created is 1 GiB. The actual size of the volume increases or decreases depending on the data stored. Temporary data volumes have redundancy level 1.

When a database instance is started, Exasol automatically creates a temporary data volume for storing the temporary tablespace of the database. This volume is automatically deleted when the database is stopped.

Volume nodes

When you create a persistent data volume you set the number of master nodes that the volume will use. The number of master nodes must match the number of active nodes in the cluster.

For example: in a cluster that will have 4 active nodes and 1 reserve node (4+1), the number of master nodes is 4.

For more information, see Create Data Volume and Create Local Archive Volume.

Data volumes grow automatically as long as enough disk space is available, typically because tables grow due to insert statements.