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Storage Classes

A storage class is a named storage backend of a cloud location. It determines how the data of your disks is physically stored, the performance characteristics of the storage and the billing units that are consumed. You choose a storage class when you create a disk or a virtual machine, and each location offers one or more storage classes depending on its hardware configuration.

Available storage classes

Depending on the location hardware configuration, available storage classes may include: software defined storage, physical storage and external storage.

Viewing storage classes

To browse the storage classes of a location

  1. Click Locations in the left menu and select the location.
  2. Open the Storage Classes tab. The storage classes enabled on the location are listed with their Name, Description and SU multiplier.
  3. Select a storage class to open its details page, where you can view its Description, its Storage unit multiplier, whether it supports templates (creating VMs from an image), and additional details about the class.

Where you choose a storage class

  • Creating disks — the disk creation wizard has a Choose Storage Class step. A panel below the selection shows the details of the chosen class and its Storage unit multiplier. When physical storage is selected, a note explains the impact on virtual machine mobility (see Limitations). For more about disk creation, see the Disks section.
  • Creating virtual machines — you choose the storage class of the boot disk. Only storage classes with template support can be used to create boot disks.
  • Restoring virtual machines from a backup — you select the storage class for each disk of the restored virtual machines.
  • Disk details and VM disks — the storage class of every disk is displayed on the disk's details page and in the disks list of a virtual machine. Selecting the class name opens its details page.

Limitations

  • Disks on physical storage are physically attached to a specific node. Virtual machines using physical storage disks cannot be moved to other physical nodes during maintenance activities or node failures. If node mobility is a critical requirement for your virtual machines, use software defined storage instead.
  • A storage class that does not support templates cannot be used to create a virtual machine from an image.

Billing

The storage class determines the billing units of a disk's storage:

  • Disks on a software defined storage class consume Storage Units (SU).
  • Disks on physical storage consume Flash Storage Units (FSU).
  • Disks on other storage classes consume Storage Units (SU) multiplied by the class SU multiplier.
  • The IOPS (speed) of a disk always consume Transaction Units (TU), regardless of the storage class.

For the full list of billing units and their definitions, see the Concepts section.