Comment 6 for bug 1375481

Looks like sometimes when massive /dev changes are expected utilities report "device or resource busy" which is related to udev's inability to handle event queue. Adding udevadm settle can help here. See for example http://permalink.gmane.org/gmane.linux.raid/34027 or http://rwmj.wordpress.com/2012/01/19/udev-unexpectedness/