Comment 22 for bug 1023755

Reviewed: https://review.openstack.org/12457
Committed: http://github.com/openstack/cinder/commit/1b3322d45fe2c5ed72cc7f8674e5e319928065ad
Submitter: Jenkins
Branch: master

commit 1b3322d45fe2c5ed72cc7f8674e5e319928065ad
Author: John Griffith <email address hidden>
Date: Wed Sep 5 19:27:48 2012 +0000

    Don't zero out snapshot volume on snapshot_delete

     When trying to zero out an LVM snapshot on precise the kernel sometimes
     hangs when performing the dd. Also the dd process itself can take
     an extremely long time even when it does succesfully complete.
     This can be up to 30 minutes for a 1 Gig volume/snapshot.

     I believe this is a kernel specific issue with LVM snapshots. The
     zeroing process is unreliable and can cause kernel hangs to let's remove it.

     In order to protect against data leakage we'll implement the zeroing process
     on volume creation. This doesn't seem to have a significant impact and doesn't
     suffer from the same isues tha zeroing out an LVM snapshot does.

     No reason to continue zero on delete, the zero on creation should
     probably be sufficient.

     Doesn't seem to cause any timing issues but need to keep this in mind.

     Fixes bug 1023755

    Change-Id: I56209d8e5973cffa997b4ec3e51c3361838386de