Image Library High Availability

You can create a highly available deployment of Private Cloud Director Image Library Service in a region by enabling image library role on multiple hosts. This feature requires the use of shared storage backend for Image Library storage. Once configured, this feature enables seamless access to images across host failures or maintenance events for hosts assigned with image library role.

Prerequisites

Following are the pre-requisites for enabling high availability for Image Library Service:

• A shared storage backend (e.g., NFS, or other block storage volume backend) is available and accessible by all hosts that will be assigned the image library role.

• All hosts that will be assigned the image library role must be located in the same region. Private Cloud Director does not support cross region image library deployment today.

• Networking and firewall rules allow image-related traffic between image library hosts and all other hosts configured with rest of the Private Cloud Director services.

Supported Storage Backends

Following table describes the supported and unsupported backends for configuring high availability for image library service.

Backend Type	HA Support
File-based (e.g., NFS)	Must be mounted on all Image Library hosts with the same path
Block Storage Volume	Recommended for scalable and resilient storage
Local File System	Not supported for HA; images will be isolated per host

How HA Works in Image Library

• When images are stored on shared storage, any image library host can serve them for VM or volume creation.

• During image creation, Private Cloud Director dynamically selects an available and healthy image library host. If one host is offline, the system transparently retries with another active host to create the image, ensuring uninterrupted service.

Deployment Steps

Step 1: Configure Shared Storage

Ensure that your shared storage (e.g., NFS or block storage) is correctly mounted or attached on each host where the image library role will be enabled.

Bash

mount -t nfs <nfs-server>:/<exported-path> /var/lib/glance/images

Configure the image library for block storage to use the volume backend in glance.conf , usually located at /etc/glance/glance.conf. This tells Glance to use Cinder to save and retrieve images.

YAML

[glance_store]
stores = cinder
default_store = cinder

Step 2: Enable Image Library Role on Multiple Hosts

1. Navigate to Infrastructure > Hosts in the Private Cloud Director UI.

2. Select the target host.

3. Click Edit Roles and assign the Image Library role.

4. Repeat this for all hosts that should serve as HA endpoints.

Info

Ensure each host has proper access to the shared image storage path.

Step 3: Validate that image library service is running

Run the following on each host enabled with image library role:

Bash

systemctl status airctl-glance

Check that:

• The airctl-glance service is active.

• No errors are reported in /var/log/airctl/glance.log.

You can also validate from the Private Cloud Director UI by checking the Settings > API Access > API Endpoints and check that image-cluster service is available with multiple Image Library endpoint.