The 69-dm-lvm-metad.rules set some udev env. variables that makes it
possible to detect the right time to activate LVM on MD. The MD is very
similar to DM during activation - it's usable only after proper device
activation - the CHANGE event. We need to make a difference between a
CHANGE event that comes from this activation and CHANGE event that is
the outcome of the WATCH udev rule (otherwise we'd end up with LVM
activation done on each CHANGE event - which is wrong).
So we need the udev databse to be persistent during pivot to root fs
even for MD devices.
Peter Rajnoha