Storage Backend Configuration

Overview

A storage backend is the combination of a driver and a physical storage system that serves Polystack Block Storage volumes. Backends are configured at deploy time through the deployment console and registered with the scheduler. Each backend must have a unique volume_backend_name that maps to at least one volume type, making it accessible to users.

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
Access to the deployment console for infrastructure-level configuration
The storage system (distributed storage cluster, LVM volume group, or NFS server) must be provisioned before configuring the backend

Supported Backends

Backend	Driver	Protocol	Use Case	HA
Distributed Storage (RBD)	`cinder.volume.drivers.rbd.RBDDriver`	RBD	Production — full replication, zero-copy clones	Yes
LVM	`cinder.volume.drivers.lvm.LVMVolumeDriver`	iSCSI	Development / single-node testing	No
NFS	`cinder.volume.drivers.nfs.NfsDriver`	NFS	Shared NAS appliances, legacy NFS integration	Depends on server
NetApp ONTAP	`cinder.volume.drivers.netapp.common.NetAppDriver`	iSCSI / NFS / FC	Enterprise NAS/SAN — FlexVol, thin provisioning, dedup	Yes
Pure Storage FlashArray	`cinder.volume.drivers.pure.PureISCSIDriver`	iSCSI / FC / NVMe-oF	All-flash arrays, high IOPS, thin by default	Yes
Dell PowerStore	`cinder.volume.drivers.dell_emc.powerstore.driver.PowerStoreDriver`	iSCSI / FC / NVMe-oF	Dell enterprise all-flash and hybrid arrays	Yes
HPE 3PAR / Primera	`cinder.volume.drivers.hpe.hpe_3par_iscsi.HPE3PARISCSIDriver`	iSCSI / FC	HPE enterprise SAN — CPG-based provisioning	Yes
Hitachi VSP	`cinder.volume.drivers.hitachi.hbsd_iscsi.HBSDISCSIDriver`	iSCSI / FC	Hitachi enterprise storage systems	Yes
IBM FlashSystem	`cinder.volume.drivers.ibm.storwize_svc.storwize_svc_iscsi.StorwizeSVCISCSIDriver`	iSCSI / FC / NVMe-oF	IBM all-flash and Storwize arrays	Yes
iSCSI (generic)	`cinder.volume.drivers.iscsi.ISCSIDriver`	iSCSI	Generic iSCSI targets not covered by vendor drivers	Depends on array
Fibre Channel (generic)	`cinder.volume.drivers.fibre_channel.FibreChannelDriver`	FC	Generic Fibre Channel targets	Depends on array

Configure a Distributed Storage (RBD) Backend

The distributed storage driver is the recommended backend for all production deployments. It uses RADOS Block Devices backed by a Polystack Distributed Storage cluster.

Web Console
CLI

Open Block Storage configuration

Select the distributed storage driver

Select Distributed Storage (RBD) from the Backend Driver dropdown.

Ensure the storage pool is created and the authentication keyring is available on all volume service nodes before completing this step.

Configure RBD parameters

Parameter	Description	Example
Pool Name	Name of the storage pool for volumes	`volumes`
Auth Username	Storage authentication user	`polystack-volume`
Keyring Path	Path to the keyring file on volume service nodes	`/etc/ceph/ceph.client.polystack-volume.keyring`
Cluster Name	Storage cluster identifier	`ceph`
Backend Name	Unique name for this backend	`rbd-ssd`

Apply and deploy

Click Save Configuration, then click Deploy Block Storage. The deployment console restarts the volume service and validates backend connectivity.

Backend configured — volume service restarted and backend registered with scheduler.

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.

Verify volume service status

List volume service endpoints

openstack volume service list

All services should show state up and status enabled.

List configured backends

List storage backends and capacity

openstack volume backend pool list --long

This shows all active backend pools registered with the scheduler, including free capacity, reserved capacity, and driver version.

Configure Enterprise Storage Backends

For NetApp, Pure Storage, Dell, HPE, Hitachi, and IBM backends, configuration is applied through the deployment console globals and Ansible. The cinder.conf sections are generated from templates. See External Storage Integration for full configuration examples, driver parameters, and volume type mapping for each enterprise backend.

Enterprise backend drivers require vendor-specific Python packages installed on the volume service nodes. The deployment console manages driver installation for supported backends during deployment.

Configure an LVM Backend

LVM backends are suitable for development and single-node testing environments only.

Web Console

Select LVM driver

In the deployment console, navigate to Configuration → Block Storage and select LVM from the Backend Driver dropdown.

Configure LVM parameters

Parameter	Description	Example
Volume Group	LVM volume group name	`polystack-volumes`
Target Helper	iSCSI helper binary	`lioadm`
Backend Name	Unique name for this backend	`lvm-local`

Apply

Click Save Configuration and Deploy Block Storage.

LVM provides no replication or redundancy. Do not use LVM backends for production workloads where data durability is required.

Backend Health Verification

After configuration, verify that the backend is registered and reporting capacity:

List backends with capacity details

openstack volume backend pool list --long

Key columns to verify:

Column	Expected Value
`free_capacity_gb`	Greater than 0 — confirms backend is reporting capacity
`total_capacity_gb`	Matches expected pool size
`driver_version`	Populated — confirms driver initialized correctly
`storage_protocol`	`rbd`, `iSCSI`, or `NFS` depending on backend type

Enable or Disable a Backend Service

Disabling a volume service prevents the scheduler from sending new volume operations to that backend. Existing volumes on the backend are unaffected. Re-enable the service to restore normal scheduling.

Disable a volume service (maintenance)

openstack volume service set \
  --disable \
  --disable-reason "Scheduled maintenance" \
  <volume-service-host> \
  cinder-volume

Re-enable a volume service

openstack volume service set \
  --enable \
  <volume-service-host> \
  cinder-volume

Troubleshooting

Backend pool does not appear in list

Cause: The volume service has not registered the backend with the scheduler, or the service is not running.Resolution:

Check service status

openstack volume service list

Look for the volume service on the affected storage node. If state is down, check service logs via the deployment console for driver initialization errors.

Backend reporting zero free capacity

Cause: The storage pool is full, or the backend driver cannot reach the storage cluster to report capacity.Resolution:

Verify distributed storage cluster health: check cluster status from the storage administration interface
Verify the authentication keyring is present on the volume service node
Verify the pool name matches the configured backend pool
Increase pool capacity or add OSDs to the storage cluster

Next Steps

External Storage Integration

Full configuration guide for NetApp, Pure Storage, Dell, HPE, and IBM backends

Volume Types & QoS

Map volume types to backends and configure QoS policies

Thin Provisioning

Configure thin and thick provisioning with overcommit ratios

Storage Tiers

Configure multi-tier storage with NVMe, SSD, and HDD backends

Backup Backends

Configure Ceph, Swift, S3, or NFS as the volume backup destination

Migration

Migrate volumes between backends for rebalancing or hardware retirement

Core Services

Other Services

Overview

Supported Backends

Configure a Distributed Storage (RBD) Backend

Open Block Storage configuration

Select the distributed storage driver

Configure RBD parameters

Apply and deploy

Authenticate

Verify volume service status

List configured backends

Configure Enterprise Storage Backends

Configure an LVM Backend

Select LVM driver

Configure LVM parameters

Apply

Backend Health Verification

Enable or Disable a Backend Service

Troubleshooting

Next Steps

External Storage Integration

Volume Types & QoS

Thin Provisioning

Storage Tiers

Backup Backends

Migration

​Overview

​Supported Backends

​Configure a Distributed Storage (RBD) Backend

Open Block Storage configuration

Select the distributed storage driver

Configure RBD parameters

Apply and deploy

Authenticate

Verify volume service status

List configured backends

​Configure Enterprise Storage Backends

​Configure an LVM Backend

Select LVM driver

Configure LVM parameters

Apply

​Backend Health Verification

​Enable or Disable a Backend Service

​Troubleshooting

​Next Steps

External Storage Integration

Volume Types & QoS

Thin Provisioning

Storage Tiers

Backup Backends

Migration

Overview

Supported Backends

Configure a Distributed Storage (RBD) Backend

Configure Enterprise Storage Backends

Configure an LVM Backend

Backend Health Verification

Enable or Disable a Backend Service

Troubleshooting

Next Steps