Description of problem: Include this functionality to future releases Currently libvirt driver doesn't support resizing disk down. https://bugs.launchpad.net/nova/+bug/1270238 Version-Release number of selected component (if applicable): How reproducible: always Steps to Reproduce: 1. Create an instance 2. resize the flavor down 3. Actual results: During a resizing down all run well and the instance is updated to the new flavor with the new disk size. but in real the disk is not resized and keep the original size. Expected results: Disk resized down too
The Nova API intentionally disallows resize down at this point due to inconsistencies in the ability to support this across various hypervisor drivers, and the inconsistent results such an operation would have to give based on how much of the disk has actually been used.