Comment # 2 on bug 917031 from Neil Brown

The problem here appear to be one of timeouts.

When md is surprised by a degraded array (i.e. the array wasn't degraded before
the reboot), it needs to wait a while for the  missing device to appear.

dracut (the early boot manager) has explicit handling for this, which is
slightly different from what happens after boot but is correct and works.

This means that all other devices should be configured to wait at least this
long.  However they aren't.

I have another bug open which has similar problems: bug#832501.

I spend a while exploring that and made some progress, but found some things
extremely hard to understand.

If I get one of these figured out I'll probably manage to fix the other one,
but for now it is a bit of a mystery.

Sorry.