[Bug 872220] Re: Fails to boot when there's problems with softraid

[Andrew Falconer]

Had an extremely frustrating experience with this bug while attempting
to re-install a Debian system with Ubuntu 12.02 x86_64, and while trying
to debug 11.10. The main issue was that by the time I was dropped to a
shell the prompt asking if I wanted to boot degraded was long and gone
from my scroll back and covered with mdadm output - the only evidence
that something was up was a "Timed Out" message with no context.

Although the install was onto a single non-raided drive, and there were
no file systems in /etc/fstab located on raid devices I experienced
constant hanging on boot as there were other non-system disks present
which were members of a RAID5 array which was unable to start. After
finally tracking this down the easiest out was to modify /usr/share
/initramfs-tools/scripts/mdadm-functions to exit out of the
degraded_arrays() and mountroot_fail() functions so I could get the
system running and work on the RAID array at a later date.

I would suggest that rather than timing out and dropping to a shell the
best default option would be to simply not start the array at all,
display a message to that effect, and let the user deal with the issue
if the system is able to boot.

If the system is not able to boot due to the raid array holding a system
volume and there are concerns about allowing arrays to start degraded by
default it is more reasonable to at least continue booting and hit an
error, such as failed to mount / (which would probably drop them to a
shell anyway), rather than stopping the boot process altogether.

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https://bugs.launchpad.net/bugs/872220

Title:
  Fails to boot when there's problems with softraid

Status in “mdadm” package in Ubuntu:
  Triaged

Bug description:
  Ubuntu 11.10 has a new feature that it warns you while booting if
  there's a program with the softraid.

  It tells you that a hard disk in the softraid is missing, then asks,
  on the console:

  Continue to boot? y/N

  But it ignores all keypresses. After 5 seconds or so it then times
  out, falls to the default "N" option, and dumps you to a emergency
  bash prompt, with no indication on how to proceed.

  The feature is a good idea, but not in the current broken state.

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