When the Block Storage service creates volumes from images, it downloads images from the Image service into an image conversion directory. This directory is defined by the 'image_conversion_dir' option in /etc/cinder/cinder.conf (under the [DEFAULT] section). By default, 'image_conversion_dir' is set to /var/lib/cinder/conversion. If the image conversion directory runs out of space (typically, if multiple volumes are created from large images simultaneously), any attempts to create volumes from images will fail. Further, any attempts to launch instances which would require the creation of volumes from images will fail as well. These failures will continue until the image conversion directory has enough free space. As such, you should ensure that the image conversion directory has enough space for the typical number of volumes that users simultaneously create from images. If you need to define a non-default image conversion directory, run: # openstack-config --set /etc/cinder/cinder.conf DEFAULT image_conversion_dir <NEWDIR> Replace <NEWDIR> with the new directory. Afterwards, restart the Block Storage service to apply the new setting: # openstack-service restart cinder