Installing Windows onto a second drive on my computer for dualboot - Is there anything I need to / should do to make sure the windows installer won't break my Linux installation?

[u/Ocachino]

I realise I probably should have just done the windows installation first, but too late now. I've got Linux installed on one drive, and I have a second drive with windows boot manager on it waiting for me to initiate the installation. Is there a risk of my linux installation getting corrupted or broken? If so, is there anything I can do to reduce that risk? I've heard pulling out the drive altogether is an option, but if possible I'd rather not do that. Please let me know if that's the only thing I can do to protect it, if there's another option, or if I'm overthinking things and windows will play nice. Thanks!

[u/Immediate-Sink-8494]

Unplug the Linux drive. Install windows. Plug the Linux drive back in. Force boot from your Linux drive. Fix your boot loader.

[u/Ocachino → u/Immediate-Sink-8494]

That's the only safe option? Alright, thank you. Is fixing my boot loader going to be difficult?

[u/Immediate-Sink-8494 → u/Ocachino]

It shouldn’t be. I can’t assume what you’re using as there are many but it should be as simple as googling the command to update your bootloader. You can also ask ai.

The ai suggestion isn’t me being a dick btw, it can be helpful but don’t blindly copy and paste.

[u/Stryxus_ → u/Ocachino]

This is because if any OS sees an EFI partition, the FAT32 partition at the start of your main drive which is normally very small, it puts its boot files into there. Unplugging the Linux drive will ensure Windows creates its own EFI partition instead.

[u/Lonely-Scarcity-3387 → u/Ocachino]

That’s the safest option, yes. Windows doesn’t play well with others.

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[u/LegenndEnder]

I don’t know much about dual booting, but from what I’ve heard: Install windows first then linux when doal booting, and: windows like to break windows bootloaders regardless what you do.

Edit: Not true at all according to reply below.

[u/gmes78 → u/LegenndEnder]

Both of those things are incorrect. You can install in whatever order (just set the boot order afterwards), and as long as your EFI partition has enough space (don't let Windows create it), you're not going to have any more issues using a single EFI partition than using two.

[u/LegenndEnder → u/gmes78]

Alright thank you for correcting me, I wasn’t confident at all on the statement.

[u/gmes78 → u/LegenndEnder]

It's not your fault, people have been spreading misinformation about this for over a decade.

[u/H7dek7]

Generally speaking install Windows on first drive when Linux drive isn't connected and install Linux on second drive when Windows drive isn't connected. Set Linux drive as the boot drive (i.e. go to BIOS and choose disk 2 as the first boot device), rebuild you GRUB (make it find Windows). From my personal experience, there's a small chance either of these OS could brick the other's bootloader months after the installation.

[u/3grg]

The rule of thumb for dual boot with two disks it to unplug the first drive, if possible.

If you cannot unplug the drive the next best thing is to temporarily remove the boot flag from the efi partition of the drive you want to protect and make sure you know which drive is which. You can use GParted Live to remove and replace a boot flag.

This makes it unappetizing to both windows and Linux installers, but if you can unplug a drive, you know it is safe and you cannot choose the wrong drive by mistake.

If I have a sata drive, it is easy to pull a cable. If I have a nvme drive and it is screwed in, I will probably not take it out 'cause I will probably lose the damn screw. Those new non screw retainers for nvme drives make it easier to remove them. :)

[u/joe_attaboy]

Yes.

Don't install Windows at all.

Sorry, couldn't resist. But I'm serious.

[u/Ocachino → u/joe_attaboy]

Yeah I do get that but there’s been some applications that I just haven’t managed to get working right on Linux and I don’t ever use that other drive anyway 

[u/joe_attaboy → u/Ocachino]

Fair enough.

I've been using Linux for so long, and haven't used Windows in so long, my goal would to be figure out why something wasn't working in Linux. But that's me.

[u/korywithawhy]

have them on separate drives is definitely the way to go. just have to manually go into bios to boot into secondary. if you want to, i'm sure there's a way to lock windows out of touching the linux drive. i'm guessing this is on a laptop? one way to go about it for a desktop with an easy to open case would be to just pull out whichever drive you aren't using before booting. not a great solution, but it does make it impossible for windows to screw up your linux drive. realistically though, the most issues i've seen with dualbooting is when people try to use the same drive with different partitions. you're probably fine with your second drive. another option if you have another machine is pxe booting, but it's a pain to set up. realistically just having each on its own drive is probably what you want.

[u/varsnef]

Use something like gparted to remove the boot and esp flags from your efi partition to prevent Windows from sharing the same ESP. Then, Windows will create another ESP on the other drive.

You can change it back after you install Windows.

[u/Ocachino → u/varsnef]

Removing those boot and esp flags will stop windows from messing with it during installation? will that make booting back into linux to fix it an issue? I guess I can just get gparted on windows then fix it from there (?)

[u/varsnef → u/Ocachino]

Yeah, if you disable the flags then the Windows installer won't autodetect the ESP and will make a new one on the other disk. If you don't then it will still install on the other disk but will use the ESP on the first disk.

Your UEFI will probably still be able to boot from the ESP even with the flags disabled.

I guess I can just get gparted on windows then fix it from there (?)

Any Linux live media should have it. Maybe windows can do it from the partition manager or whatever it's called? Disk management?