How does the installer decide

[Bret Busby]

On 04/05/2021, Grizzly via ubuntu-users <ubuntu-users at lists.ubuntu.com> wrote:
> Hi All
>
> Tried to install 21.04 on a PC with 20.04.3 & Win7 it only offerd to erase
> (20.04) and install or "something else"
>
> But when I tried to install 21.04 on a PC with 16.04.6 it offerd to install
> along side 16.04.6, Erase and install or "something else"
>
> So why?
>
> Given the problems (some) people have had with installing 21.04, I didn't
> want
> to lose what is a working system, (yet) in favour of 21.04
>
>
>

If you have, or, can create, by reducing the size of an existing
partition or partitions, free space, or, a free partition, I recommend
choosing the "something else" option, then you can choose to boot an
existing installation, or the 21.04 installation.

I now have three systems, upon which the "something else" option was
used for installing 21.04 - one has also now, 20.10 and an MS Windows
(I think it is 10, but I can not remember) version, one has  also
20.04 and MS Windows 7, and one has also 20.04, 16.04.7, and an
unusable (I forgot the password, because it was too difficult to use)
MS Windows 8 installation.

On each system, at each reboot, I can choose which OS to boot.

So, I recommend "something else".

If you have a legacy BIOS only system, apparently, as I found, I could
ignore the threat of catastrophic destruction, that appears, to
successfully complete and use the 21.04 installation.

-- 
Bret Busby
Armadale
West Australia
(UTC+0800)
..............