Volume Types and QoS (Admin)

Overview

Volume types are the mechanism through which administrators expose storage tiers to users. Each volume type maps to a specific backend through the volume_backend_name extra spec and optionally enforces I/O quality-of-service limits. Well-defined volume types are essential for predictable workload performance and efficient backend utilization.

Administrator Access Required — This operation requires the admin role. Contact your Polystack administrator if you do not have sufficient permissions.

Prerequisites

Administrator credentials with the admin role
At least one storage backend configured and registered with the scheduler
Backend names available via openstack volume backend pool list --long

Create a Volume Type

Dashboard
CLI

Navigate to Volume Types

Navigate to Storage > Volume Types (admin view).

Create the type

Click Create Volume Type. Enter a descriptive name (e.g., nvme, ssd, standard) and an optional description. Click Confirm.

Set the backend association

In the volume type list, click the type name to open its details page. Under Extra Specs, click Create and add:

Key	Value	Purpose
`volume_backend_name`	`<backend-name>`	Routes volumes to the correct backend

The value of volume_backend_name must exactly match the volume_backend_name configured in the backend driver settings. Use openstack volume backend pool list to confirm the correct name.

Verify

Create a test volume using the new type and confirm it reaches available status:

Test volume type

openstack volume create --size 1 --type <type-name> test-vol
openstack volume show test-vol -c status -c type
openstack volume delete test-vol

Volume type created and validated against the backend.

Authenticate

Source your credentials file to authenticate with the Polystack platform:

Load credentials

source openrc.sh

Your administrator provides the RC (credentials) file for your project. See CLI Setup for configuration details.

Create the volume type

Create volume type

openstack volume type create \
  --description "NVMe-backed high-performance storage" \
  nvme

Set the backend association

Set extra spec for backend routing

openstack volume type set \
  --property volume_backend_name=nvme-backend \
  nvme

Set as default (optional)

Set default volume type

openstack volume type set --default ssd

The default type is used when users create volumes without specifying a type.

Verify

List volume types with properties

openstack volume type list --long

Volume type visible with correct backend association.

Configure QoS Policies

Quality-of-Service specs enforce I/O limits on volumes associated with a type. QoS policies are applied at the hypervisor (front-end), at the storage backend (back-end), or at both layers.

Dashboard
CLI

Create a QoS Spec

Navigate to Storage > Volume Types (QoS Specs tab, admin view). Click Create QoS Spec. Enter a name (e.g., ssd-standard-qos) and set the consumer:

Consumer	Effect
`front-end`	Limits enforced at the hypervisor (recommended for RBD)
`back-end`	Limits enforced at the storage backend
`both`	Limits enforced at both layers

Add I/O limit specs

After creation, open the QoS Spec and add limits:

Key	Example Value	Description
`total_iops_sec`	`5000`	Maximum combined read + write IOPS
`read_iops_sec`	`3000`	Read IOPS limit
`write_iops_sec`	`2000`	Write IOPS limit
`total_bytes_sec`	`524288000`	Throughput cap in bytes/sec (500 MiB/s)
`read_bytes_sec`	`314572800`	Read throughput cap (300 MiB/s)
`write_bytes_sec`	`209715200`	Write throughput cap (200 MiB/s)

Associate with a volume type

Switch to the Volume Types tab. On the target volume type row, click Manage QoS Spec (the first row action). In the dialog, select the QoS spec from the table and click Confirm.

QoS spec associated with volume type — limits active on all new volumes.

Create a QoS spec

Create QoS spec for SSD tier

openstack volume qos create \
  --consumer front-end \
  --property total_iops_sec=10000 \
  --property total_bytes_sec=1073741824 \
  ssd-standard-qos

Associate with volume type

Associate QoS spec with volume type

openstack volume qos associate ssd-standard-qos ssd

Verify association

Show volume type with QoS

openstack volume type show ssd

Volume type ssd is now enforcing QoS limits for all new volumes.

Restrict Volume Type Access

By default, volume types are available to all projects. Sensitive types (e.g., encrypted or high-performance tiers) can be restricted to specific projects:

Make a volume type private

openstack volume type set --private <type-name>

Grant access to a specific project

openstack volume type access add \
  --project <project-id> \
  <type-name>

List projects with access

openstack volume type access list <type-name>

Recommended QoS Values by Tier

Tier	total_iops_sec	total_bytes_sec	Consumer
NVMe	50,000 – 200,000	4,294,967,296 (4 GB/s)	`front-end`
SSD	5,000 – 20,000	1,073,741,824 (1 GB/s)	`front-end`
Standard	500 – 2,000	314,572,800 (300 MB/s)	`front-end`

Start with conservative limits and adjust based on observed workload behavior. Overly restrictive QoS on shared backends can throttle legitimate I/O and cause application timeouts.

Next Steps

Storage Tiers

Configure NVMe, SSD, and HDD tier mappings and set the default volume type

Encryption

Enable at-rest encryption on volume types

Storage Backends

Configure and manage the underlying backend drivers

Volume Types (User)

User guide for selecting the correct volume type for a workload

Core Services

Other Services

Overview

Create a Volume Type

Navigate to Volume Types

Create the type

Set the backend association

Verify

Authenticate

Create the volume type

Set the backend association

Set as default (optional)

Verify

Configure QoS Policies

Create a QoS Spec

Add I/O limit specs

Associate with a volume type

Create a QoS spec

Associate with volume type

Verify association

Restrict Volume Type Access

Recommended QoS Values by Tier

Next Steps

Storage Tiers

Encryption

Storage Backends

Volume Types (User)

​Overview

​Create a Volume Type

Navigate to Volume Types

Create the type

Set the backend association

Verify

Authenticate

Create the volume type

Set the backend association

Set as default (optional)

Verify

​Configure QoS Policies

Create a QoS Spec

Add I/O limit specs

Associate with a volume type

Create a QoS spec

Associate with volume type

Verify association

​Restrict Volume Type Access

​Recommended QoS Values by Tier

​Next Steps

Storage Tiers

Encryption

Storage Backends

Volume Types (User)

Overview

Create a Volume Type

Configure QoS Policies

Restrict Volume Type Access

Recommended QoS Values by Tier

Next Steps