Cause: Bug in ThinLVM driver caused by an incomplete backport to upstream stable/grizzly branch caused regression in upstream 2013.1.4
Consequence: ThinLVM volume driver attempts to clear volume data using an incorrect path which does not exist, so snapshot deletion will fail if volume clearing is enabled. (Enabled by default.)
Fix: Make a stable/grizzly-only fix for the ThinLVM volume driver
Result: Snapshot deletion now works with the ThinLVM volume driver
Cause: LVM behavior changed in RHEL 6.5 so that Thin snapshot volumes do not automatically have devices generated in /dev/mapper/.
Consequence: Snapshot deletion fails for ThinLVM because it tries to wipe a device that does not exist.
Fix: Disable wiping for ThinLVM as has been done for Havana.
Result: Cinder snapshot operations now behave as expected.