Unable to install grub in /dev/sda

[Liam Proven]

On Tue, 19 Oct 2021 at 12:19, Phil Fraser <phillor9 at gmail.com> wrote:
>
> I have installed Xubuntu 21.10 alongside Windows 10 on a mechanical drive but I cannot get past the installation of grub on the SSD. Debian 9 with a Raspberry Pi desktop (32 bit version) is the only version of several distributions that has been successful. I now suspect that the SSD has some some of compatibility problem. I'm reluctant to reformat the drive because it still has a working version of Windows 10 on it even though I cannot access it (except with Raspberry Pi Debian 9 version) because of the grub problem.
>
> The default boot mode is both UEFI and legacy with legacy mode first. If I change that to legacy only, then the USB stick (built with startup disk creator) won't boot.

Did you try Ventoy as I suggested?

> My first SSD was a Samsung. Everything was good except that I could't reboot Linux even though Windows 7 would reboot. I now have a Crucial MX500 2.5 SSD which was good until I tried to overwrite version 20.10 with a later version. Both SSDs are 1TB. Can anyone recommend a SSD that's known to be suitable to use with my Thinkpad T420? I have a no-brand 110GB SSD that I might try tomorrow. It's too small to be useful.

The brand should not matter.

What matters is this:

• If you installed Windows in UEFI boot mode, you _must_ install
xBuntu in  UEFI mode too. You cannot mix them.
• You should only have 1 ESP per drive. Use custom partitioning and
mount the ESP to /boot/efi
• You do not install GRUB to the MBR with UEFI boot. It installs a
shim in the ESP.
• You will need a separate tiny partition of type BIOS_BOOT for the rest of GRUB

Personally, I find all this too complex. So on my 420 I disabled UEFI
boot, partitioned with MBR, no ESP, and reinstalled Ubuntu in BIOS
mode.

It sounds to me like this may be your best option but you will, I
think, have to reinstall Windows.

ISO files are a free download from
https://www.microsoft.com/en-gb/software-download/windows10ISO

A single 16GB USB key can hold both at once with Ventoy.

Move your Windows data files to a separate partition first, then back
them up, and then you can just restore them later.

Here's how my disk is laid out:

[Windows reserved]
[Windows C drive]
Extended partition
    {
      [Shared data drive, NTFS]
      [Ubuntu root]
      [Ubuntu home]
      [Ubuntu swap]
    }

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