Install windows after already having Manjaro

Hey, i would like to install windows. i already have manjaro for about a year now and i cant lose my files.

I would like to free up 500Gb for windows but i heard that Windows will replace Grub.

i also know i can reinstall grub with this tutorial: GRUB/Restore the GRUB Bootloader - Manjaro

i use UEFI
Now i just want to make sure what i am doing is safe, here are the steps i am going to take:

  1. I will use a usb to open Windows installer
  2. resize the current 3.60 tb drive to 3.1 tb
  3. create a new partition for windows
  4. install windows on it
  5. Now i have windows working, but grub has been replaced!
  6. i use my other live usb to boot up into Manjaro Live USB
  7. follow the guide to reinstall grub

is this correct?

other questions:
everytime i update windows will i need to re do the grub install?
whats the chances it will corrupt / delete my files?
is it possible to make it so Windows cannot access my Manjaro drive (just wanting to make sure that if one day something happens on windows it wont access manjaro.)? (not a problem if not possible)
Will this corrupt my bios or cause problems in anyway? (Even if i do it correctly)

Now i also have another question, if i use a totally new SSD, that i will buy and install on my pc will it still delete grub or does that not have to do anything with it?

then do a backup of your important data to an external device before any further action.
no backup no mercy …


Of course, i just want to know what the chances are from them being deleted

You have to shirink the ext4 partition from a manjaro live usb session. Otherwise correct. There is no way to absolutely protect the ESP from windows (the 100MB green partition), it is not messed up on every update but 1-2 times a year.
Windows will not see the ext4 and never touch anything there.


That’s also my experience (Win10) but, as you predicted, it will mess it up at first install!

Unless you accidentally hit ‘use the whole disk’ when installing Windows. Win can not ‘see’ the content of the partition but it can erase it, so, as @Olli said, “do a backup”.


Can you explain what you mean by “Windows will not see the ext4 and never touch anything there.”. What is located in ext4? My friend helped me Install manjaro a year ago and i lost contact with him so i do not know what is on there.

What’s in ext4 = manjaro and all your files.


Oh right Thanks, i thought fat32 but i just looked again and saw ext4, i am guessing fat32 is the boot loader?

Also, so sorry for asking too many questions, i am just trying to understand this and dual boot as i need it for lots of projects

I’m not sure you can install Windoof on a partition beyond 2 TB of the start…

It would be better to save the big amount of user data from your ext4 partition and to shrink the Linux partition to let’s say 100 GB or what ever needed for the application part. Then Windoof could be installed at a partition within the first 2 TB.

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More or less. It’s your EFI system partition. It contains the boot loaders for every operating system on your drive.

Best is to create a second ESP for Wintendo, because if you don’t, then as @6x12 says, Wintendo will regularly mess up your ESP in an attempt to claim the whole computer for itself.

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What if i use another ssd? i am planning to just buy a 1tb (or 500 gigs) ssd and i dont have a problem with using it for windows

That would work. But create an ESP on that one there then, so that it won’t mess with the ESP on your Manjaro drive.

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How can i do that, and after i do that do i need to use “sudo update-grub” (thats what i learned from google) to boot into windows?

The Windows installer should normally allow you to create an ESP on that drive. But I’m not sure, as I don’t use Windows. I only know about Windows from what I read about it, and that’s not very flattering. :joy:

Yes, but after editing /etc/default/grub in order to enable the os_prober — which you only need to run once, so after it has found Windows and added it to the GRUB menu, you must edit the file again in order to disable the os_prober again.

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So let me just make sure i understand:

  1. I install windows on the new ssd
  2. i boot back into Manjaro and enable os prober and then update grub
  3. then check if it added windows to the grub list
  4. then disable prober
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Using a second ESP partition or drive will reduce the risk of windows overwriting something at least on minor/quarterly updates. You should be aware that there is no absolute guarantee. I have done exactly that, and than i updated the bios from the windows tool and kaboom… i had to restore grub. So keep the manjaro flash usb close. The problem is, the UEFI boot process has two components - the loader on the ESP partition (the little green thing), and the UEFI variables. And every OS have access to these (and can write or delete them), even if the disk component is excluded.

While at /etc/default/grub also check some of the other settings, because the grub menu is hidden by default. It is easier to have a menu instead of hitting ESC every time you need to switch the OS


Okay thanks!

Let me correct the above list:
Between 1 and 2 you will have to follow the guide to restore grub
Forget 4: if you are dual booting you need os prober enabled. On every kernel update (at least once a month) in manjaro the grub menu list is regenerated and you obviously need windows to appear there.

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fingers crossed

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will i need to follow the restore grub guide even if i install it on a diff SSD?