Bug#664581: rootdelay workaround

[Ross Johnson <ross@homemail.org>]

I found a better workaround.  Let's move this to wishlist for mdadm.

Workaround for my system is to put the following in /etc/default/grub:
  GRUB_CMDLINE_LINUX="rootdelay=9"

I would like a better solution, something that 1) forces mdadm to wait
for all its components before assembling the arrays and continuing with
the boot and 2) has a safety timeout to continue the boot regardless.
This could take the form of specifying what arrays need to be assembled
at boot time (i.e. /dev/md0, /dev/md1, and /dev/md2), repeatedly polling
every second to find what drives are available and to which arrays they
belong, and a final timeout setting to continue with the boot attempt
even if not all components are ready.  The above should also handle the
case where a raided drive (like /dev/md1) is used as a component in
another sofware raid that is needed for boot.

Ross