Comment 15 for bug 75681

From the changelog of mdadm 2.5.6-7ubuntu4:
     Specify --no-degraded argument to mdadm in initramfs; this
     can be overridden by setting MD_DEGRADED_ARGS to some nonempty value
     (eg, a single space). This ought to fix race problems where RAIDs are
     assembled in degraded mode far too much. (LP #75681 and many dupes.)

This looks much more like a work arround than a real fix! I may misunderstand it, please ignore me if this is the case :)
Does it mean that I have to enter commands in the initramfs or to do some kind of black magic to boot a system with a broken hard drive ?
And it only avoids to desynchronise a working RAID, it does not fix the race at boot time as mdadm does still try to assemble the array with too few drives and thus refuses to assemble it properly later.

The array should _not_ be started _at_all_ unless all needed devices have been detected (including spare ones) OR when all device detection is done.
So I ask it again, is it any way to make udev send a special signal when devices detection is finished ?
Is it any way to make mdadm scan for arrays and assemble them ONLY if all of their devices are present, doing _nothing_ otherwise ?

It may be tricky but I think that these problems can only be fixed this way.
Anyway, it did work before.