[Bug 1318351] Re: mdadm doesn't assemble imsm raids during normal boot

[Anders Sjölund]

This bug also affects when you fresh install 14.04 to a (Intel) fakeraid mirror array. 
The installer finds the imsm signature and asks if you want to install on a mdadm array.
But the installer picks upp the "nomdmonddf nomdmonisw" grub config, and the server then boots using dmraid.

What I then need to do is comment out the line in /etc/default/grub.d/dmraid2mdadm.cfg, and run dpkg-reconfigure mdadm and reboot.
This time mdadm is configured correctly, and the /dev/md126 device is used instead of /dev/mapper/isw...

I hope this will be addressed in future releases, and it would not hurt
if there is an official note on this.

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https://bugs.launchpad.net/bugs/1318351

Title:
  mdadm doesn't assemble imsm raids during normal boot

Status in “mdadm” package in Ubuntu:
  Confirmed

Bug description:
  I have a non-root Intel "fakeraid" volume which is not getting
  assembled automatically at startup. I can assemble it just fine with
  "sudo mdadm --assemble --scan".

  While trying to debug this, I encountered that it is being assembled
  when I'm booting in debug (aka recovery) mode. It turns out that
  nomdmonisw and nomdmonddf are passed to the kernel during normal boot
  only, and this is due to /etc/default/grub.d/dmraid2mdadm.cfg
  containing:

  GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT nomdmonddf
  nomdmonisw"

  Commenting out that line fixes the problem.

  I've gathered that this is an effort to migrate from dmraid to mdadm
  for fakeraids. I don't understand how it's supposed to work, but in my
  case dmraid is not installed, and this setting is an interference.
  (The background is that I recently added a 3 TB raid1 and was
  therefore forced to abandon dmraid in favor of mdadm since the former
  doesn't handle volumes larger than ~2 TB. So I dropped dmraid and set
  up mdadm from scratch for this new raid.)

  Also, I believe it's a bug that these kernel arguments are different
  between normal and recovery boot.

  My mdadm is 3.2.5-5ubuntu4 in a fresh trusty install.

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