I'm not entirely convinced that is a duplicate too.
Additionally to the messages already reported I also see upstart-udev-bridge restarting while creating the snapshots from time to time:
upstart-udev-bridge[25372]: Disconnected from Upstart
init: upstart-udev-bridge main process (25372) terminated with status 1
init: upstart-udev-bridge main process ended, respawning
I'm not entirely convinced that is a duplicate too.
Additionally to the messages already reported I also see upstart-udev-bridge restarting while creating the snapshots from time to time: udev-bridge[ 25372]: Disconnected from Upstart
upstart-
init: upstart-udev-bridge main process (25372) terminated with status 1
init: upstart-udev-bridge main process ended, respawning