Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/variable-size-root-disk.

Description:

Currently all image size checks are made against the root disk size in the flavor, which is then treated as the absolute size of the root disk to create, overriding the min_disk value of the image and the image size itself.    However when working with a range of images (for example a mix of Windows and Linux) it would be better to be able to use a single set of flavors whilst still honoring the min_disk value of the image.  This would allow, for example, more efficient snapshots for images that do not need the full size of root_gb.     

This blueprint allows the root disc size to vary within the constraints specified by the image Creator (via image metadata ) and the Cloud Provider (via flavors)  


Specification URL (additional information):

https://wiki.openstack.org/wiki/VariableSizeRootDisk