Number of caches copies of images by cinder

Issue

• We enabled the image_volume_cache_enabled = True in our cinder.conf, as described here: https://docs.openstack.org/newton/admin-guide/blockstorage-image-volume-cache.html
• In the cinder-internal project, we see the cached images being created in the form of volumes.
• However, for the same image, several volumes are being created. We were unable to understand the pattern that cinder applies for making a new copy of a cached image into a new volume.
• Before starting a new copy sometimes it uses the image for creating 2 insances and sometimes 40, as far as we could observe.
• We would like to understand this process a little better.