How to clean up full /boot safely?

[Liam Proven]

On 12 February 2018 at 13:51, Colin Watson <cjwatson at ubuntu.com> wrote:
>
> OK, at this point (and in most of the rest of it) you're just having a
> go at my idiolect.

No, I am really not.

I am a native English speaker living in a non-English-speaking country
and I am currently working in my 4th job over here in
non-English-based companies, almost entirely with colleagues who are
not native speakers.

Avoiding ambiguity is a life skill for me.

Also, whereas I cheerfully admit that you've picked me up on errors
plenty of times and it's good that you do it, both for me to learn,
and so that I do not misinform others -- despite that, I am pretty
tech-savvy. I've been a tech pro for 30 years.

So *no*, this is *not* about your language. It is about your message.

Your paranoid assumption that I am attacking your use of language
appears to have blinded you to my actual point.

Which is this stuff is _not guaranteed_. It is _not_ known safe,
absolutely reliable, rock-solid "this will just work if your computer
is functioning".

This is a case of "if nothing is weird and if you've done it the right
way, this stuff _should_ work, probably, and you _ought to be able_ to
do it.

And _that_ is my point.

I am not willing to rely on ought to, should, probably, almost all the
time stuff.

I want "this WILL WORK" without caveats.

If you install GRUB onto the MBR of a smallish disk with a plain MBR
partition with plain filesystem in a Linux-centric filesystem, *it
will work*.

Promise, guarantee.

Yes the hardware might be iffy. The user might have mispartitioned the
disk. They might have forgotten to format it. All sorts of qualifiers,
but if it was done right, it WILL work.

This _cannot_ be said of a software RAID or of a non-Linux filesystem
or of any arbitrary kernel on any arbitrary distro.

If, for instance, my server wouldn't boot and all I had was a Fedora
or Debian boot USB, and /boot and / were on ZFS, I probably could not
read it or fix it.

That is not acceptable to me.

If they are on a simple partition on ext4, *any* distro will let me
fix it, and then boot it, and when it boots, then I can get at the
weird stuff on a striped ZFS filesystem.

And if I can't, if it's a plain ZFS stripe set with no weird bootable
volumes and zero executable files, then I should be able to boot the
dead server off a FreeBSD stick and read that volume.

That's what I demand.

I am not willing to do anything which requires special measures.

I am *not* picking at your English. I am addressing your point: that
"it ought to work" is not good enough for me.

> One thing I particularly enjoy about developing GRUB (specifically GRUB
> 2 rather than 0.9x - the latter has some similar ideas but in a much
> more primitive form)

I am glad you enjoy hacking on it, and I'm glad it exists.

However, TBH, I personally have alway found GRUB arcane and I don't
like it as a tool.

My testbed machine at home uses Powerquest BootMagic as its boot
manager, not GRUB, _because_ I find it arcane and I wanted to avoid
working with it.

> It's obviously fine to be technically-conservative.  But you made a very
> specific claim which went above and beyond merely not wanting to use
> more complex facilities:
>
>   "the kernel must be on something GRUB can read, i.e. a straightforward
>   Linux filesystem."
>
> I called you on that claim, because it's incorrect; GRUB can read more
> than just straightforward Linux filesystems, and has been able to do so
> in one form or another for well over a decade.  If you meant "e.g."
> rather than "i.e.", then that would be different.

I meant "that is".

A Linux kernel software RAID is _not_  a straightforward Linux
filesystem. A ZFS volume set isn't. Anything encrypted or striped or
mirrored isn't.

Even btrfs isn't. I have personally in the last month rendered a
testbed server booting off btrfs unbootable because of something I
did. I don't know what but I couldn't fix it.


-- 
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