I ran into this issue myself and was trying to figure out how to solve it. Examining the initrd image which had been created, the 63-md-raid-arrays.rules and 64-md-raid-assembly.rules files were absent. As mentioned in #789150, mdadm now has its own /usr/share/initramfs-tools/hooks/mdadm which *should* copy those two files into any initrd which is created.
When I regenerated the initrd by running `update-initramfs -u -k all`, the two udev rules files *were* present. Looking at things there are two things I /suspect/ may have happened. First, when initially building the image for this system I was working from a qemu image. Reliability was handled outside of qemu and hence the mdadm package didn't include itself into the initrd. Perhaps the mdadm initramfs hook script should treat a value of "MODULES=most" as an indicator to *always* include itself into the initrd (this IS a hint that something major may change soon). Second, perhaps the issue was the mdadm package was installed /after/ the kernel and bootloader packages were installed so the initial ramdisk image was never rebuilt. Perhaps this indicates mdadm's postinst script needs to preemptively run `update-initramfs -u -k all` after installation (similar situation for postrm). -- (\___(\___(\______ --=> 8-) EHM <=-- ______/)___/)___/) \BS ( | ehem+sig...@m5p.com PGP 87145445 | ) / \_CS\ | _____ -O #include <stddisclaimer.h> O- _____ | / _/ 8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445
