Installing Manjaro over existing debian in a dual boot system

Dear everyone,

I’m trying to install Manjaro in the following environment:

  • Thinkpad T450s, grub2 dual boot Win10 and Debian.
  • The operating systems are on two physically separate disks, Disk0 is for Win, Disk1 is for Debian.

The win10 partitioning tool gives the following information (sorry can’t embed media):

  • Disk0. C: is Boot, Page File, Crash Dump, Primary Partition
  • Disk0. E: is Primary Partition
  • Disk0. D: is Primary Partition
  • Disk1. has three partitions. Total is about 224 GB, approximately 28 GB + 11,7 GB + 184 GB.

When installing Manjaro, at the step the disk for installation is to be chosen I chose disk1 and go with the option “erease partition” - this seems to be the right choice.
My question is: what choice should I make about the bootloader? I have absolutely no idea for this one, I’d appreciate any help.

What are the options?

You do need a boot loader - and you can’t use the one from the then no more existent Debian.
What choice is it that you struggle with?

see this

There are four choices for the bootloader location:

  • a bootloader on the MBS of Disk0
  • a bootloader on the MBS of Disk1
  • System partition
  • Do not install a bootloader.

Based on your answer I’d think the fourth option is the right choice, and once the installation is finished, manjaro will just show up in the grub2 menu at startup, right?

I saw this but I’m not quite sure this is relevant in my case

That would be a misunderstanding - you cannot use the one that belonged to the prior Debian installation.
… well, perhaps you can - but you probably shouldn’t …

I’m not at all sure about that. If you are willing to gamble and just try … go ahead
and be prepared to fix it afterwards.

I’d vote for the system partition - so both installed systems can be booted.
That is most likely the place where your current boot loader is installed to.

It would be good if you remembered what was done when you installed Debian.

Hi @Nachlese, thanks, I’ll give it a try and hope for the best.
Vielen Dank für Deine Hilfe!

If you erase Debian’s partition, you should also override its bootloader with Manjaro’s. Otherwise, your choice of not overriding it will be kept and the bootloader settings won’t be updated.
You can override it later, but you likely won’t gain anything by delaying that.

This seems to be the case as now I’m stuck at the grub rescue console.Before destroying everything on my laptop, can I simply reinstall manjaro with the bootloader option “MBS on Disk1” or should I try to solve the issues through the rescue console?

Nothing will be destroyed - you just cannot boot.

Did you boot both systems through grub before?
Then install grub to the system partition (as you called it earlier).

and make sure you know whether Windows was installed in legacy mode or in UEFI mode - and that you used the same mode to install Manjaro

The BIOS was earlier set to work both with legacy and UEFI, priorize legacy and CSM enabled. Debian was installed on the second disk and the debian-themed grub menu worked flawlessly - unfortunately I don’t remember how or where it was installed.
When installing Manjaro I did not have the choice for uefi or legacy.
Depending on the setting in the BIOS the laptop will now boot directly to Manjaro (UEFI mode) or to a grub menu missing the Win10 option (legacy/uefi with CSM). I’ll look into the option legacy only.
Choosing the boot drive directly did not result any change, I could not boot Win10 since the first time the grub rescue prompt came.

Perhaps not the best idea, but I started a new topic on the dual boot issue, when I saw the data being intact here. In that thread I included the output of some of the usually required commands - care to take a look and move this conversation?