How to clean up full /boot safely?

[Colin Watson]

On Mon, Feb 12, 2018 at 09:35:30PM +0100, Liam Proven wrote:
> But I own machines where there is a single boot hard disk setting in
> the BIOS and if that drive fails it is not possible to specify a
> failover device.

Whoa.  Back up.  The end of your question, the one that Tom and I were
both replying to, was:

  If it is on both, and /dev/sda fails, if the firmware is configured so
  that the secondary boot device is /dev/sdb, will GRUB automatically
  failover and boot off /dev/sdb? If so, will it bring the kernel up
  normally with a degraded RAID pair?

  Is it possible to give a definite canonical answer to this, without
  referring to firmware versions, BIOS restrictions, motherboard
  support, etc?

Here, "if the firmware is configured so that the secondary boot device
is /dev/sdb" implies that it's possible to do so on the firmware in
question.  Now you're moving the goalposts: suddenly, the firmware
cannot be configured in that way, and you're criticising us for not
considering the case that you specifically excluded from consideration.
I don't know about Tom, but I would certainly have given a different
answer if you hadn't *specifically ruled out that case* in your
question.

Bad form.

> There are setups where it _might_ not work, and that kind of thing is
> why people like me write manuals which carefully say "this might work
> but don't rely on it", and why some people use /boot filesystems even
> today, which is the point of this thread.

I certainly wouldn't argue that a separate /boot is always wrong.  (Ralf
said something along those lines, I think.)  I do think that it causes a
different class of problems, some of which prove to be difficult in
their own way for users to deal with, and so it's worth trying to avoid
them in more situations than has traditionally been the case.  Perhaps I
have a different set of biases due to having spent more time dealing
with that class of problem than you have; I don't know.  But this is
just a difference in degree, not in kind.

And I don't think either of us know whether the original poster in this
thread has a complicated system where a separate /boot is worthwhile
(even if not strictly required), or a simple one where it's really just
unnecessary complexity ...

-- 
Colin Watson                                       [cjwatson at ubuntu.com]