Description of problem: Currently the LVM driver in libvirt will unconditionally call 'dd' upon volume delete. Cinder meanwhile has a variety of config options for this # Method used to wipe old voumes (valid options are: none, # zero, shred) (string value) #volume_clear=zero # Size in MiB to wipe at start of old volumes. 0 => all # (integer value) #volume_clear_size=0 Nova needs to support these exact same options to provide 100% parity of functionality between images and volumes.
To test this, setup nova with [DEFAULT] libvirt_images_type=lvm libvirt_images_volume_group=as_setup_on_your_system [libvirt] # Select one of zero,none,shred volume_clear=zero Then verify that when deleting images that: 1. Start and then delete an instance, then veryify that dd if=/dev/zero ... writes to the volume being deleted. You should have time to see the dd process writing zeros as it's generally in the GB range (the size of the root disk). 2. Change the volume_clear setting above to 'none', and restart nova, and a new instance and verify that on deletion the dd process is not run
*** Bug 1057371 has been marked as a duplicate of this bug. ***
When set to 'zero', the dd process was visible in the task list for several seconds, while on 'none' the lvm volume just quickly disappeared without triggering dd. Verified.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2014-0231.html