Creating and Managing Volume Groups in OpenStack

Volume groups in OpenStack allow you to organize related Cinder block storage volumes into logical collections and manage them as a single unit. This is particularly useful when you need coordinated snapshots across multiple volumes, such as a database data volume and its associated log volume, or any set of volumes that must remain consistent with one another.

This guide covers everything you need to know about volume groups in OpenStack Horizon: creating groups, selecting group types, adding and removing volumes, and safely deleting groups when they are no longer needed.

What Are Volume Groups?

Volume groups are a Cinder feature that lets you bundle multiple volumes together under a shared management context. A group is defined by a group type, which determines what operations are allowed on the group as a whole.

The most common use case is group snapshots: snapshotting all volumes in a group simultaneously to capture a crash-consistent point-in-time state. This is essential for any multi-volume workload where data consistency across volumes is required.

Volume groups are distinct from server groups (which govern instance scheduling). Volume groups apply only to block storage.

Prerequisites

Before creating a volume group, confirm the following:

• You have access to the OpenStack Horizon dashboard with Project-level permissions
• At least one group type has been configured by your cloud administrator
• You have existing volumes available, or you plan to create new volumes to add to the group
• All volumes you intend to group are in the same availability zone

Note: Volume group types must be created by an administrator before users can create groups. If no group types appear during group creation, contact your cloud administrator to configure them.

Understanding Group Types

A group type is a named configuration that defines what capabilities a volume group supports. Think of it as a policy applied to the group that governs which operations are permitted.

Group types are configured by administrators and typically expose one or more of the following capabilities:

• Consistent group snapshot support: Enables coordinated snapshots across all volumes in the group
• Storage backend capabilities: Some backends expose additional group-level features depending on the driver

When selecting a group type during group creation, choose the one that matches your operational requirements. If you need group snapshots for disaster recovery or backup workflows, confirm that the group type supports consistent_group_snapshot_enabled.

You can view available group types in Horizon by navigating to Project > Volumes > Group Types (this section is visible if your role has appropriate permissions).

How to Create a Volume Group in Horizon

Creating a volume group is a two-step process: first you create the group itself, then you add volumes to it.

Step 1: Create the Group

1. Log in to the Horizon dashboard
2. Navigate to Project > Volumes > Groups
3. Click the Create Group button in the upper right
4. In the Create Group dialog, complete the following fields:

• Name: Enter a descriptive name for the group (for example, db-primary-group)
• Description (optional): Add context about what this group contains or why it exists
• Group Type: Select from the available group types. This determines what operations the group supports
• Availability Zone: Select the availability zone where your volumes reside. All volumes added to this group must be in the same zone

5. Click Create Group to confirm

The new group will appear in the Groups list with a status of Available.

Step 2: Add Volumes to the Group

After creating the group, you need to populate it with volumes.

1. In the Project > Volumes > Groups list, locate your newly created group
2. Click the dropdown arrow next to the group's Edit Group button
3. Select Edit Group from the actions menu
4. In the Edit Group dialog, you will see two panels:

• All Available Volumes: Lists volumes that match the group's volume types and are not yet assigned to a group
• Selected Volumes: Lists volumes currently in the group

5. Click on volumes in the All Available Volumes panel to move them to Selected Volumes
6. Click Save to apply the changes

Volumes added to the group will continue to function normally. Group membership does not change how a volume is attached to instances or how it operates day-to-day. It only affects group-level operations such as snapshots.

Important: A volume can only belong to one group at a time. If a volume is already in a group, it will not appear as available for other groups.

How to Add Volumes to an Existing Group

If you need to add more volumes to a group you have already created:

1. Navigate to Project > Volumes > Groups
2. Find the group you want to modify
3. Click the dropdown and select Edit Group
4. In the Edit Group dialog, select additional volumes from the All Available Volumes panel
5. Click Save

The newly selected volumes are added to the group immediately. There is no downtime or interruption to attached instances.

How to Remove Volumes from a Group

Removing a volume from a group does not delete the volume. The volume remains available and can be attached to instances or added to a different group.

1. Navigate to Project > Volumes > Groups
2. Locate the group containing the volume you want to remove
3. Click the dropdown and select Edit Group
4. In the Edit Group dialog, find the volume in the Selected Volumes panel
5. Click on it to move it back to All Available Volumes
6. Click Save

The volume is removed from the group and its status returns to Available as a standalone volume.

How to Create a Group Snapshot

If your group type supports consistent group snapshots, you can snapshot all member volumes simultaneously:

1. Navigate to Project > Volumes > Groups
2. Locate the group you want to snapshot
3. Click the dropdown next to the group and select Create Group Snapshot
4. Enter a Name and optional Description for the snapshot
5. Click Create Group Snapshot

The group snapshot captures all member volumes at the same point in time. This is the primary reason to use volume groups for multi-volume workloads like databases, where data and log volumes must be consistent with each other.

Group snapshots appear under Project > Volumes > Group Snapshots.

How to Manage Volume Groups Using the OpenStack CLI

For users who prefer the command line or need to automate group management, the OpenStack CLI provides full group management capabilities.

Create a Group

1. List available group types to find the one you need:

1   openstack volume group type list
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2. List available volume types (required when creating a group):

1   openstack volume type list
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3. Create the group, specifying a group type and one or more volume types:

1   openstack volume group create \
2     --name db-primary-group \
3     --group-type GROUP_TYPE_NAME \
4     --volume-type VOLUME_TYPE_NAME \
5     --availability-zone nova \
6     --description "Primary database volume group"
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Add Volumes to a Group

Use the volume update command to assign a volume to a group:

1openstack volume set --group GROUP_ID VOLUME_ID
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Replace GROUP_ID with the group's UUID and VOLUME_ID with the target volume's UUID.

Remove a Volume from a Group

To remove a volume from its group without deleting it:

1openstack volume set --no-group VOLUME_ID
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List Groups and Group Details

1openstack volume group list
2openstack volume group show GROUP_ID
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Create a Group Snapshot via CLI

1openstack volume group snapshot create \
2  --name db-snapshot-2026-02-24 \
3  --description "Consistent snapshot before maintenance" \
4  GROUP_ID
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How to Safely Delete a Volume Group

Deleting a volume group removes the group container but does not automatically delete the member volumes. However, there are important rules to understand before proceeding.

What Happens to Member Volumes

By default, when you delete a group, the member volumes are not deleted. They become standalone available volumes again. You can choose to delete the volumes as part of the group deletion by selecting the appropriate option.

Deleting a Group in Horizon

1. Navigate to Project > Volumes > Groups
2. Locate the group you want to delete
3. Click the dropdown and select Delete Group
4. In the confirmation dialog, you will see an option: Delete Volumes

• Leave this unchecked if you want to keep the member volumes after the group is removed
• Check this box only if you intend to permanently delete all member volumes along with the group

5. Click Delete Group to confirm

Warning: If you check Delete Volumes, all volumes in the group will be permanently deleted. This action cannot be undone. Ensure you have snapshots or backups of any data you need to preserve before proceeding.

Deleting a Group via CLI

To delete a group without deleting member volumes:

1openstack volume group delete GROUP_ID
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To delete a group and all its member volumes simultaneously:

1openstack volume group delete --force GROUP_ID
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The --force flag instructs Cinder to delete the group and all its volumes in a single operation. Use this only when you are certain the data is no longer needed.

Common Group Management Scenarios

Consistent database backups: Group a database data volume and log volume together. Create a group snapshot before maintenance windows or schema migrations to ensure you have a consistent recovery point that covers both volumes.

Pre-upgrade checkpoints: When upgrading application stacks that span multiple volumes (application data, configuration, state), create a group snapshot before the upgrade. If the upgrade fails, you can restore all volumes to their pre-upgrade state from the group snapshot.

Multi-volume workload isolation: Group volumes by application or environment to track which volumes belong to which workload. This does not enforce any access restrictions but improves operational clarity when managing large numbers of volumes.

Decommissioning workloads: Use groups to identify all volumes associated with a decommissioned service. Delete the group with the Delete Volumes option checked to clean up all associated block storage in a single operation.

Next Steps

With volume groups configured, you can build reliable backup workflows using group snapshots and coordinate storage management across multi-volume workloads. If you need to explore additional volume management capabilities, review the guides on creating and managing volumes, working with volume snapshots, and managing volume backups in OpenStack Horizon.