[gentoo-user] Grub and multiple distros on LVM [was duplicate gentoo system ...]

[Grant Edwards]

On 2020-11-24, antlists <antlists@××××××××××××.uk> wrote:
>
>> Cool, I'll have to read up on using volumes for that. How far back in
>> time can you go before you get to distros that would have problems?
>
> How old is LVM? It's been around for ages, I think.

We regularly run into customers running distros that came out 10 years
ago. Not long ago, I was working with a customer who was running RHEL 6
and kernel 2.6.32 on production machines.  Yes, RHEL 6 is still
supported (though not for long).  According to the LVM Wikipedia page,
2.6.32 is old enough that journalling filesystems didn't work
correctly on top of LVM. That said, it's quite possible RH backported
LVM improvements to 2.6.32 so that's not an issue.

Right now, I have a small "grub" partition which has menu that allows
chainloading any of dozen or so main partitions, each of which has a
linux distro installed (with a bootloader installed in that
partition). I've been reading up on LVM vs. grub, and all of the
examples I find of booting multiple distros on LVM don't seem to be
chainloading. Rather they point the "master" grub at the root
"partition" and that partition's .cfg file.  However, that assumes
that the distro uses grub, and that the .cfg file is compatible with
the "master" grub executables.  I'd rather not rely on that assumption
and just do chainloading like I always have.

In grub, does chainloading an LVM virtual partition work the same as
chainloading a "real" partition?

--
Grant