Volume service¶

Volumes are persistent block storage devices that can be attached to instances. Unlike ephemeral storage that is tied to the instance lifecycle, volumes exist independently and persist even when instances are deleted. This makes them suitable for boot disks, databases, and any data that should outlive a specific instance.

This page includes OpenStack CLI commands. See the API Access documentation for instructions on how to install and configure the command line client.

Volume types¶

Safespring Compute offers two volume types:

Type	Use case	Read IOPS per GB	Write IOPS per GB	IOPS range
fast	Boot disks, databases, applications with high I/O requirements	100	50	Up to 100000 read / 50000 write
large	Data archives, log storage, backups, infrequently accessed data	2	2	50–4000 read / 50–4000 write

For example, a 10 GB fast volume provides 1000 read and 500 write IOPS, while a 100 GB large volume provides 200 read and 200 write IOPS.

Info

IOPS limits apply to all mounted volumes on an instance, not just boot drives. Keep this in mind when attaching additional volumes.

It is recommended to use fast for boot volumes since a large boot volume will make the instance noticeably slower. See the Flavors documentation for more details on IOPS per volume type.

Creating a volume¶

Using the Horizon dashboard¶

Navigate to Volumes and click Create Volume.
Give the volume a name.
Under Volume Source, select Image if you want to create a bootable volume, or No source, empty volume for a data volume.
Select the volume type: fast or large.
Set the size in GB. If you selected an image as source, the minimum size is pre-filled.
Click Create Volume.

Using the CLI¶

Create an empty volume:

openstack volume create --size 20 --type fast my-data-volume

Create a bootable volume from an image:

openstack volume create --size 20 --type fast --image ubuntu-24.04 my-boot-volume

Attaching a volume to an instance¶

Using the Horizon dashboard¶

In the Volumes listing, select Manage Attachments from the dropdown menu on the volume. Select the instance you want to attach it to and click Attach Volume.

Using the CLI¶

openstack server add volume my-instance my-data-volume

After attaching, the volume appears as a new block device inside the instance (for example /dev/sdb). You need to format and mount it before use:

# Identify the new device
lsblk

# Create a filesystem (only for new empty volumes)
mkfs.ext4 /dev/sdb

# Mount it
mkdir -p /mnt/data
mount /dev/sdb /mnt/data

Detaching a volume from an instance¶

Warning

Always unmount the volume from within the instance before detaching it. Detaching without unmounting causes a hard disconnect from the I/O subsystem, which risks data loss.

# Inside the instance
umount /mnt/data

Then detach the volume:

Using the Horizon dashboard¶

In the Volumes listing, select Manage Attachments from the dropdown menu and click Detach Volume.

Using the CLI¶

openstack server remove volume my-instance my-data-volume

Extending a volume¶

You can increase the size of an existing volume. The volume must be detached from any instance before extending.

Using the Horizon dashboard¶

In the Volumes listing, select Extend Volume from the dropdown menu and enter the new size.

Using the CLI¶

openstack volume set --size 50 my-data-volume

After extending and reattaching the volume to an instance, you also need to resize the filesystem inside the instance to use the new space:

# For ext4 filesystems
resize2fs /dev/sdb

# For XFS filesystems
xfs_growfs /mnt/data

Deleting a volume¶

A volume must be detached before it can be deleted.

Using the Horizon dashboard¶

In the Volumes listing, select Delete Volume from the dropdown menu.

Using the CLI¶

openstack volume delete my-data-volume

Note

Snapshots taken from a volume are independent and will remain even after the volume is deleted. These snapshots continue to consume storage quota. See the Snapshots HOWTO for details on managing snapshots.

Changing volume type¶

It is possible to migrate between the fast and large volume types using the API or the UI.

Prerequisites¶

The volume has to be detached from any instance for the migration to work.

Please make sure to unmount the volume from within the instance before detaching it. The volume will be detached from the I/O subsystem of your instance, so not removing it properly could cause a "hard" disconnect, with risk of data loss.

Migrating using the UI¶

Find the correct volume using the Volumes tab of your compute project.
Select Change Volume Type in the pulldown menu for the volume you want to migrate.
Select the new volume type from the pulldown list
Set Migration policy to On demand
Click Change Volume Type

The volume service will now copy the volume from the old backend to the new. Depending on the size of the volume, this operation will take some time.