Volumes Overview

Volumes are used to store data in Exasol and are assigned to a storage disk. Refer to Storage Overview for more information on disk layout. You can view the volumes in your Exasol system by going to Services > EXAStorage:

Volume Types and Purposes

There are two types of volumes in Exasol:

  • Data volumes
  • Archive volumes

A typical Exasol setup contains at least one data volume and an archive volume. When a database instance is started, Exasol creates a temporary data volume for storing temporary database data.

Volumes in Exasol serve three different purposes:

Volume Purpose Volume Type Description
Storage of Persistent Data Data

For storing the persistent data of a database. These data volumes have the following characteristics:

  • The Volume 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.
  • Usually have a redundancy of '2'.
Storage of Archive Data Archive

For storing compressed backups of a database. Archive volumes have the following characteristics:

  • The Volume Size parameter of the volume determines the maximum size of the volume.
  • Usually have a redundancy of '2'.
  • Two kinds of archive volumes:
    • Local archive volume if stored in the cluster.
    • Remote archive volume if stored outside the cluster.
  • Expired backups are automatically removed if the volume is running out of space (only applicable to local archive volumes).
  • Volume size cannot be decreased, and can only be increased manually.
Storage of Temporary Database Data Data

For storing the temporary tablespace of a database instance. Temporary volumes have the following characteristics:

  • Are automatically created when a database instance is started, and are automatically deleted when the database instance is stopped.
  • Have a redundancy of '1'.
  • Are created with an initial size of 1GiB.
  • The actual size of the volume increases or decreases depending on the data stored.

Volume Nodes

When creating a data volume or a local archive volume, you set the number of master nodes the volume will use and assign the master nodes to the volume. Master nodes are the active nodes in a cluster. For example: in a cluster that will have 4 active nodes and 1 reserve node (a '4+1' setup), the number of active nodes, and thus master nodes, is 4.

In the case of data volumes for storing persistent database data, the number of master nodes must match the number of active nodes you set when you create the database.

Manage Volume Capacity

Automatic growth, shrink on demand

Volumes grow automatically as long as enough disk space is available, typically because tables grow due to insert statements. Volumes can be shrunk by clicking the Action shrink on the EXASolution Instance page.