Possible future dual boot with two EFI partition's on two SSD's

The situation: On this weekend, I should finally receive all my hardware for my new setup.

I want to use UEFI/GPT with Secure boot OFF. So far, I only used BIOS/MBR.

I want to give it a go with NO windows installed on the system because I did not boot it for some months now.

What I want to do:
Install Manjaro on my new m.2 SSD as single operating system with architect and GPT and grub. According to my research, that should create a EFI partition so that it is bootable and should use grub.

If I get into the situation that I need Windows again, I am going to install it on a second (m.2) SSD with GPT. During the installation of Windows 10, I would remove the Linux-SSD so that Windows thinks it is the only system present and creates its own EFI partition on its SSD.

In my theory, after the installation of windows is finished, I then would add the Linux SSD again, tell the UEFI to boot from the Linux SSD as primary boot device, run update-grub there (with os-prober) and the system should then be in a dual-boot enabled state with a working Windows entry in grub.

Am I right with that?

My data HDD and data SSD will remain BIOS/MBR formatted, but they will not contain any OS. That should also cause no problems, or am I wrong there?

sorry to says but you are WRONG

Bios can only boot on one EFI at time with option Boot and ESP , no more than one disk in this case.
make a try with 2 DE manjaro on each SSD , you will see after with gparted which ones have boot & esp

i have tried many install EFI on many disks , but Bios will only use in this case the disk with option boot , not the others.options boot is always required for EFI , you have no boot if disks are ESP only

other trouble coming is Windows update , they change options ( like fastboot , etc .. ) without any manual action , and remove entry EFI Bios that do not have a Bootx64.efi or i think do not have a real boot Microsoft ( Apple do the same thing keeps only disks with his own Os System installed )

and you should always use GPT with EFI with all your disks.

see this for more details

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what is ESP? Never heard of that before in terms of boot and partitions. (and never read of that while I tried to answer my questions myself with wiki's and guides)

thats ok for me, I want to have grub handle the boot selection afterwards.

from what I understand in that topic, his problem is created because he uses only one EFI partition for several Manjaro installations - and in BIOS, you get one entry for one EFI partiton, no matter how many OS'es that are installed in that EFI partition (at least that's what I understood from several wiki's and other guides on the net).

Thanks, will have to research on that a bit further then, because that would require me to store terabytes of data on other disks while I reformat my data disks to GPT.

this : Capture%20d%E2%80%99%C3%A9cran_2018-05-11_10-20-16

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Thanks. According to the arch wiki that esp flag is simply what defines the partition as EFI partition.

That leads me to the conclusion that what I want to do is possible:
Two EFI partitions should be shown as 2 boot options in BIOS, but of course I can only boot one at a time (the one with grub on it) - grub should be able to switch the boot to windows (at that time, BIOS does not manage boot devices anymore).

Currently, I have that exact setup with BIOS/MBR: 1 SSD with Linux and its boot partition as primary boot device, another SSD with Windows and its boot partition. Windows 10 updates never mingled with the boot partition of my Linux SSD (and I did at least 2 major release updates on Windows 10).
What I am not sure about is how that will change with EFI, but I guess I will have to try and wait for the next major Win10 update (if I end up installing Windows at all).

Nah, you can just choose windows disk in boot menu (usually F12 on post screen) and it will boot fine. Booting windows from grub is just more convenient.

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a EFI partition, ESP and $esp are all the same. (I use the term $esp).
The answers to all your questions in your first post is correct.
You can do all that.

Just a suggestion: pre-partition your new disk first.
Use gparted, at 'device' tab' --> 'Cretae Partition table' --> select 'gpt'
Then make your partitions.
One partition in fat32, 150 MB (that I'll call the $esp)
The rest are the usual.
I don't recommend a separate /boot partition.
When during installation besides the usual selection of root partition, select that 150 MB fat32 partition as mount point /boot/efi and proceed with installation.

And yes, that link which stephane posted is for multiple manjaro's.

Just a word of caution; some recent installations does not create nicely an efi entry.
See this link, prepare for it if it does not make an entry and do the [UEFI - additional commands] part after step 6 if you face some problems.

Good luck. Let us know, ya. And let us know computer make and model.

Oh, as for windows, as said, it's okay the way you outlined in your first post.
And after booting up Manjaro (as per Chris25), do a 'update-grub' and it will have the windows entry in your grub.cfg (even though it is in different disks)
You may have to select manjaro entry as first bootorder to make sure this grub is always booted up at when you start your computer (without needing to do Chris25 method (F12) each time).
Check at manjaro terminal
Refer output of manjaro as xxxx, windows as yyyy and so on.
Then do 'sudo efibootmgr -o xxxx,yyyy,zzzz,......'
where xxxx is the manjaro entry, yyyy the windows entry and so on.
Then Chris25 method will not be necessary.

Good luck.

ps: @Chris25, you may want to try that yourself (sudo efibootmgr -o xxxx,yyyy,zzzz,…).
Just be sure both windows and manjaro are in uefi/gpt.
And assuming manjaro is not on a removable disk.


That is sorta equal to changing boot order in uefi settings, isn't it?

I personally have a little bit funny setup. I usually have two ssd's - system and data, but when I need windows I swap second ssd for hdd (thinkpad ultrabay) and just start it from single boot menu. I don't use windows often so it's not a problem. I would rather run windows from external esata drive but sadly esata port on my T520 is just placeholder.

thanks for all your replies.

I know that :wink: The post above mine was just a bit misunderstandable. But thanks anyway :slight_smile:

Board will be an Asus X470-F ROG Strix Gaming Mainboard with a AMD Ryzen 7 2700X CPU and a Samsung 960 EVO 500GB m.2 SSD and 2x8GB TridentZ RGB 3200MHz DDR4 RAM.

If I decide to install Windows, I will use either my old Samsung SSD 840 PRO 256GB SATA3 SSD that runs my current MBR Manjaro installation (reformated to GPT) or buy a new m.2 SSD with ~250GB data (the board was chosen by me because it has has 2 m.2 PCIe slots, one x4, the other x2)

My main data disk is a 3TB Seagate HDD with 1.5TB ext4 partition and a 1.5TB NTFS partition with MBR formating (reason for that partition format where due to former dualboot times where I still used windows a lot, NTFS has significantly less performance when running games on it, compared to ext4).

My second data disk will be a Samsung 840 EVO 250GB that is running my current windows installation (at the moment in MBR format, but that one could be changed to GPT when formating it as data disk)

that depends if I really install Windows - at the moment I see no reason because all games and programs I currently use are running fine in Linux (only WoW and Twitch (used only as extension manager for WoW) need Wine, the rest is native).
I just wanted to make sure that my theory is right. If installing Windows before Manjaro would be easier, I would have done that now, but from what I understand that would only be the case if I only had one hard drive available and that one harddrive would need to host everything.

Yes, your theory is right. If you plan windows to have a separate $esp for itself, it does not matter if windows is installed before or after manjaro. And as for one or many hard drives, I don't find that matters at all.

And some Asus have some sightly complicated uefi setups (Some MSI 's are worse). This link here will help should you face similar problems. Hopefully not.

I guess you've all the necessary information now to proceed. Good luck.
Hmmm, I might just use this topic should anyone asks about dual-booting in uefi. :laughing:


Yes, that command is for changing bootorder in uefi.
Understand, you have a swap bay. Okay then.

If those swap bays are anything like removable drives, then a '--removable' parameter in the grub-install command (for linux, not sure for windows) can be used and you won't have to press F12.

sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=manjaro --recheck --debug --removable



I guess that this won't apply to me as I am not going to remove my mainboard battery :wink:

Can only test earliest tomorrow (F*** DHL) or on Monday/Tuesday.

[OT]: The original package arrived LAST friday with shipping damage, CPU had a crack and mainboard box was also damaged - Handled the return with the mailorder business which also had some small problems which led to CPU and mainboard being shipped separately with one day appart. The mainboard has now arrived. (package again damaged, but the content including the mainboard box is undamaged this time)
The CPU (that was shipped one day earlier then the mainboard) has not arrived on the start package center after its pickup on Tuesday, investigation started today -.- .... One time I do not order stuff through Amazon ... [/OT]

Thanks at all who helped here!

Manjaro Gnome installed on the GPT partitioned m.2 SSD with a 300MB /boot/efi partition, the MBR formated HDD is perfectly accessible at the same time (when booted up). Did not install Windows yet, let's see how long I can live without it ^^

@gohlip I installed Windows now (Overwatch is still a pain to play on Linux)

To remove my m.2-SSD I would have needed to remove my GPU, my CPU-cooler and 2 heatspreaders (not an intelligent design) so I installed Windows while the m.2 SSD with Linux was still active in the system.
m.2 can't be disabled in UEFI, but I disabled the Boot option.

Windows 10 1803 Pro installed on my 840 Pro SSD with its own EFI-Partition without me telling it to do so :wink:
Everything works as expected now: I have 2 Boot Options in UEFI: Manjaro on m.2, Windows on SSD.
Activated Manjaro as default boot option in UEFI, updated grub, and Grub now offers to boot Manjaro and Windows.

So: Everything works as expected.

Good to hear. In many cases, UEFI handles boots better than bios-legacy.
We just need to get used to it.
Cheers, take care.

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