How to Enable Image Cache in Block Storage

Problem

Creating volumes from images can be slow, especially when the same image is used repeatedly. This can lead to increased I/O load and longer provisioning times. Enabling image caching in PCD's Block Storage (Cinder) service can significantly improve performance by storing a cached copy of frequently used images.

Environment

• Private Cloud Director Virtualization - v2025.4 and Higher
• Private Cloud Director Kubernetes – v2025.4 and Higher
• Self-Hosted Private Cloud Director Virtualization - v2025.4 and Higher
• Self-Hosted Private Cloud Director Kubernetes - v2025.4 and Higher

Procedure

1. Edit Cinder Backend Configuration: On the host where the Persistent Storage (or Cinder Volume) role is enabled, add the following parameters in the [DEFULT] section of the /opt/pf9/etc/pf9-cindervolume-base/conf.d/cinder.conf

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image_volume_cache_enabled

image_volume_cache_max_count

image_volume_cache_max_size_gb

For Example:

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image_volume_cache_enabled = True

image_volume_cache_max_count = 50

image_volume_cache_max_size_gb = 200

2. After updating the configuration, restart the pf9-cindervolume-base service for the changes to take effect:

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$ sudo systemctl restart pf9-cindervolume-base

Validation

Check if Image Cache is Enabled: Verify the effective configuration using the following command on the cinder node:

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$ grep image_volume_cache /opt/pf9/etc/pf9-cindervolume-base/conf.d/cinder.conf

Additional Information

What Each Parameter Means:

• image_volume_cache_enabled: Enables or disables the image caching mechanism.
• image_volume_cache_max_count: Limits the number of images to cache. If the limit is reached, the least recently used (LRU) image will be evicted.
• image_volume_cache_max_size_gb: Limits the total size (in GB) of all cached images. The LRU policy also applies here when the limit is hit.