Best way to boot windows and linux on seprate disk?

Ask Fedora
1

hey yall!

I’m trying to figure out the best way to have Linux and windows on a separate disk. I’ve dual; booted them, but I would like them to be separate if I can help it.

I’ll pretty much only be using windows for School (my college requires it) and anti cheat that wants kernel level access. (CS2 Faceit)

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Maybe not the best way but very easy (if you use sata SSDs, see fn) - only have the relevant drive connected when installing. E.g. for a clean install of Fedora, disconnect your Windows drive and install Fedora to the connected drive. After installation reconnect the Windows drive obviously. (Make sure the PSU is swithced off and any residual current discharged - after turning off the psu, push the ‘on’ button to start the PC - before disconnecting / reconnecting drives and take precaustions re elctro-static discharge .)
To chose which system to boot into: select the appropriate boot disk in bios (usually accessed by pressing del or f2 etc. after starting the machine).
fn: If you use an, e.g., an m2 ssd you can still use this approach but it get’s a little nasty if one or more of your drives sits under a GPU or a CPU cooler.

3

Personally I recommend differently.

  1. install the new drive that will be used for fedora.
  2. install fedora on the new drive and only allow the installer to access that drive.
  3. boot fedora and grub should show the ability to boot either fedora or windows.

Having the second drive connected is not normally an issue since you can select which drive is used for the installation. If you do not have both drives installed then grub will not see the windows installation and you are forced to use the bios to select the boot device. If both drives are connected then grub will normally enable booting windows and the grub menu will show during boot to allow the selection.

3 Likes
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Jeff if you follow this way - probably a better way - and you upgrade Windows (10->11) or Windows just does something that breaks grub, you’ll need to do some grub maintenance to fix up your Fedora, correct?

5

I have a laptop that I have been dual booting with fedora & windows 10 for years. The windows updates do not affect grub for me.

If you do a repair or recovery of the windows installation it may affect grub when using a shared efi partition. But when using 2 different drives, with each having its own efi patition, even that should not break grub. since windows would not alter the second efi partition on the second drive.

The one big thing to watch for would be if windows alters the boot order, which then might require using bios to initially boot fedora and recover.

I do not plan to upgrade to win11 so do not know how that might affect it. Friends I have that use win11 have told me that recent upgrades have forced the use of bitlocker on windows and that seems to break some things

6

I currently have only fedora installed on an m.2 ssd and from what you are saying, if I install windows on a separate ssd grub should see it? Similar to how it would look if I had both installations on the same drive, i.e., like traditional dual booting?

tbh im not opposed to having to go into BIOS and selecting a boot disk, it’s not like I’ll be switching back and forth all day. I do 99% of gaming and everything else on Linux.

EDIT: And honestly, I mess up and break my Fedora install all the time messing around with stuff and I reinstall if often, lol. It’s a pain if windows is installed alongside it.

7

Relatively easy with EFI with both blank disks:

  1. Install Windows to 1 drive first
  2. Disconnect it
  3. Install Linux to 2nd drive
  4. Reconnect 1st drive
  5. Have GRUB re-probe boot devices
  6. Set GRUB’s EFI (Fedora’s shim) as primary/first boot
  7. Boot either Linux or Windows from GRUB

That way:

  • Windows has no idea about Linux existing during initial set-up
  • Linux doesn’t re-use Window’s EFI partition
  • Neither OS re-uses the other’s EFI partition for anything
  • Linux GRUB updates just update the EFI file; as long as GRUB is ok, Windows and Linux can boot
  • Windows bootloader updates don’t touch anything with GRUB (since Windows has its own EFI partition)
  • Even though Windows can see Linux’s EFI partition later; the initial Windows install was done only with Window’s EFI partition existing, so there’s no hard-coded reason to touch any other EFI partition

Other:

  • Wiping out Windows drive should leave Linux/GRUB alone
  • Wiping out Linux/GRUB should allow switching to Window’s EFI boot primary (both Linux and Windows write their bootloaders to EFI vars)
  • Booting Windows EFI-direct from BIOS/firmware shouldn’t affect anything (can’t do Windows boot → Linux but back-to-back Windows reboots might make setting it temp-primary ideal)
8

When windows is shutdown during the fedora install it would not care anything about what else is being done.

With 2 drives and installing only on the second drive fedora would not access the windows efi on the other drive. Fedora would create a new efi partition on the drive where it is being installed.

Leaving the windows drive connected allows the bootloader to identify and add windows to the grub menu without the need to manually update grub after the drive is reconnected.

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what if I dont have a windows drive and I reeeeeally dont want to reinstall fedora and set up everything the way I like.

10

If it’s a hassle to remove / disconnect then reconnect the Fedora / m2 drive, you could:

  1. Use clonezilla to make a copy of your existing Fedora drive;
  2. Install windows onto a second drive (Windows will mess up your Fedora drive);
  3. Use clonezilla to restore the pre-windows state of your Fedora drive. (Windows may try to scan this drive next time you boot into Windows from the bios, hit a key to tell it to stop that.)
    There are better ways I’m sure it you like doing sys-admin - I don’t.