Backup Backends

Overview

Polystack Block Storage backups are managed by the cinder-backup service, which stores volume backup data in a configurable backend. The backup backend is independent of the volume backend — backups from any volume backend (Ceph, NetApp, LVM) can be stored in any backup backend (Ceph, Swift, NFS, S3). Selecting the right backup backend depends on your recovery time objectives, storage capacity, and existing infrastructure.

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

Prerequisites

The cinder-backup service must be deployed and running
The backup backend must be network-accessible from the backup service nodes
Credentials and endpoint configuration must be available before deployment

Supported Backup Backends

Backend	Driver	Transport	Use Case
Ceph RBD	`ceph`	RBD protocol	Native Ironcore — incremental backups, fast restores
Swift	`swift`	HTTP/S	Built-in object storage, multi-node replication
NFS	`nfs`	NFS	Shared NAS appliances, on-premises tape replacement
S3-compatible	`s3`	HTTPS	AWS S3, Ceph RGW, MinIO, Dell ECS, any S3 endpoint
Google Cloud Storage	`google`	HTTPS	Off-site cloud backup to GCS buckets
IBM Spectrum Protect (TSM)	`tsm`	TSM API	Mainframe-connected enterprise backup with TSM

Backend Configuration

All backup backend settings are placed in the [DEFAULT] section of cinder.conf. Only one backup backend is active at a time.

Ceph RBD — recommended for Ironcore

The Ceph backup driver stores backups as RBD images in a dedicated backup pool. It supports incremental backups — only changed blocks are transferred after the first full backup, making subsequent backups fast and space-efficient.

cinder.conf — Ceph backup backend

[DEFAULT]
backup_driver = cinder.backup.drivers.ceph.CephBackupDriver
backup_ceph_pool = backups
backup_ceph_user = cinder-backup
backup_ceph_conf = /etc/ceph/ceph.conf
backup_ceph_keyring = /etc/ceph/ceph.client.cinder-backup.keyring
backup_ceph_chunk_size = 134217728
backup_ceph_stripe_unit = 0
backup_ceph_stripe_count = 0
restore_discard_excess_bytes = true

When both the volume backend and backup backend are Ceph, the backup driver can perform server-side RBD-to-RBD copies without moving data through the backup service node, reducing network load and backup time significantly.

Swift (Object Storage)

The Swift backup driver stores backup data as objects in a Swift container. Each backup chunk is stored as a separate object. This backend benefits from Swift’s built-in replication for durability.

cinder.conf — Swift backup backend

[DEFAULT]
backup_driver = cinder.backup.drivers.swift.SwiftBackupDriver
backup_swift_url = http://10.0.1.71:8080/v1/AUTH_
backup_swift_auth = per_user
backup_swift_auth_version = 3
backup_swift_user = cinder
backup_swift_key = <swift-key>
backup_swift_container = volumes_backup
backup_swift_object_size = 52428800
backup_swift_retry_attempts = 3
backup_swift_retry_backoff = 2
backup_compression_algorithm = zlib

NFS

The NFS backup driver mounts a remote NFS share and writes backup files to the mount point. It is suitable for organizations with existing NAS infrastructure.

cinder.conf — NFS backup backend

[DEFAULT]
backup_driver = cinder.backup.drivers.nfs.NFSBackupDriver
backup_mount_point_base = /var/lib/cinder/backup_nfs
backup_share = 10.0.10.100:/export/cinder-backup
backup_file_size = 1999999999
backup_sha_block_size_bytes = 32768
backup_enable_progress_timer = true

The NFS share must be exported with write permissions for the cinder-backup service account. Add the export to /etc/exports on the NFS server:

NFS server — /etc/exports

/export/cinder-backup  10.0.0.0/8(rw,sync,no_subtree_check,no_root_squash)

S3-Compatible

The S3 backup driver works with any S3-compatible endpoint including AWS S3, Ceph RADOS Gateway, MinIO, Dell ECS, and Wasabi. Set backup_s3_endpoint_url for non-AWS endpoints.

cinder.conf — S3-compatible backup backend

[DEFAULT]
backup_driver = cinder.backup.drivers.s3.S3BackupDriver
backup_s3_endpoint_url = https://s3.example.com
backup_s3_store_access_key = <access-key>
backup_s3_store_secret_key = <secret-key>
backup_s3_store_bucket = cinder-backups
backup_s3_object_size = 52428800
backup_s3_retry_attempts = 3
backup_s3_retry_backoff = 2
backup_compression_algorithm = zlib
backup_s3_ssl_insecure = false

For AWS S3 without a custom endpoint, omit backup_s3_endpoint_url and set the region:

cinder.conf — AWS S3 backend

[DEFAULT]
backup_driver = cinder.backup.drivers.s3.S3BackupDriver
backup_s3_store_access_key = <aws-access-key>
backup_s3_store_secret_key = <aws-secret-key>
backup_s3_store_bucket = my-cinder-backups
backup_s3_store_region = ap-south-1
backup_compression_algorithm = zlib

Google Cloud Storage

The GCS backup driver stores backups in a Google Cloud Storage bucket. Authentication uses a service account credentials file.

cinder.conf — Google Cloud Storage backend

[DEFAULT]
backup_driver = cinder.backup.drivers.google.GoogleBackupDriver
backup_gcs_bucket = my-cinder-backups
backup_gcs_object_size = 52428800
backup_gcs_block_size = 32768
backup_gcs_retry_attempts = 3
backup_gcs_retry_backoff = 2
backup_gcs_credential_file = /etc/cinder/gcs-credentials.json
backup_compression_algorithm = zlib

The service account must have storage.buckets.get, storage.objects.create, storage.objects.get, and storage.objects.delete permissions on the target bucket.

IBM Spectrum Protect (TSM)

The TSM backup driver integrates with IBM Spectrum Protect (formerly Tivoli Storage Manager) for enterprise tape and disk backup workflows.

cinder.conf — TSM backup backend

[DEFAULT]
backup_driver = cinder.backup.drivers.tsm.TSMBackupDriver
backup_tsm_volume_prefix = cinder
backup_tsm_password = <dsm-password>
backup_tsm_compression = true

The TSM client (dsmc) must be installed and configured on the backup service node, and the DSMI_CONFIG environment variable must point to the active dsm.sys configuration file.

Apply Backup Backend Configuration

In Ironcore deployments, backup backend settings are configured through the deployment console and applied via Ansible. Do not edit cinder.conf directly.

Apply backup configuration changes

ironcore-ansible deploy --tags cinder

After deployment, verify the backup service is running:

Check backup service status

openstack volume service list --service cinder-backup

Verify a Backup

Dashboard
CLI

Create a test backup

Navigate to Storage > Volumes, select a volume, and click the More dropdown and select Data Protection > Create Backup.Set a name and leave the snapshot field empty for a full backup.

Monitor backup status

Navigate to Storage > Volume Backups. The backup transitions through creating to available.

Restore the backup

Click the More dropdown and select Restore to restore to a new volume. Confirm the restored volume matches the original in size and status.

Backup created and restored successfully — backend is operational.

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 a backup

openstack volume backup create \
  --name test-backup \
  <volume-id>

Wait for backup to reach available state

openstack volume backup show <backup-id> -c status

Restore backup to a new volume

openstack volume backup restore \
  --name restored-vol \
  <backup-id>

Verify restored volume

openstack volume show restored-vol -c status -c size

Next Steps

Backups (User Guide)

End-user guide for creating, managing, and restoring volume backups

Storage Backends

Configure primary volume backends for block storage

External Storage

Connect to NetApp, Pure Storage, Dell, and HPE enterprise arrays

Encryption

Encrypt volumes at rest — works independently of backup backend

Core Services

Other Services

Overview

Supported Backup Backends

Backend Configuration

Apply Backup Backend Configuration

Verify a Backup

Create a test backup

Monitor backup status

Restore the backup

Next Steps

Backups (User Guide)

Storage Backends

External Storage

Encryption

​Overview

​Supported Backup Backends

​Backend Configuration

​Apply Backup Backend Configuration

​Verify a Backup

Create a test backup

Monitor backup status

Restore the backup

​Next Steps

Backups (User Guide)

Storage Backends

External Storage

Encryption

Overview

Supported Backup Backends

Backend Configuration

Apply Backup Backend Configuration

Verify a Backup

Next Steps