Arch Linux

agena10

Member

Registered: 2020-10-30

Posts: 10

[SOLVED] How much space do Grub need to dual boot with Win10?

I have a fresh Win10 installed and the system reserve partition only has 50mb (my previous Win10 had ~500mb as system reserve partition). Apparently it is by design now, since Windows 10 version 2004, that the system reserve partition only has 50mb. Before that version 2004, system reserve partition was ~500mb.

I am worried it might not be enough to install Grub with it for dual boot to work. May I know what are my options?

Last edited by agena10 (2020-11-03 08:40:32)

Awebb

Member

Registered: 2010-05-06

Posts: 6,688

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

$ du -sch /boot/grub
13M     /boot/grub
13M     total

Standard installation without any extra stuff.

Copy-pasta of ncdu /boot/grub:

    3,9 MiB [##########] /locale
    3,1 MiB [#######   ] /x86_64-efi
    2,8 MiB [#######   ] /themes
    2,3 MiB [#####     ] /fonts
    8,0 KiB [          ]  grub.cfg
    8,0 KiB [          ]  grub.cfg.example
    4,0 KiB [          ]  grubenv  

So, you could probably slim this out a bit.

agena10

Member

Registered: 2020-10-30

Posts: 10

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

This is mine by the way.

$ du -sch /boot/grub
12M	/boot/grub
12M	total

But aren't initramfs, vmlinuz, intel-ucode files going to be there too in system reserve partition? I won't be having a /boot partition since if I understood it right, I am at max capacity partitions of 4 as I have MBR system. My partitions are below by the way:

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 931.5G  0 disk
├─sda1   8:1    0    50M  0 part
├─sda2   8:2    0 195.3G  0 part
├─sda3   8:3    0 540.9G  0 part
└─sda4   8:4    0 195.3G  0 part

sda1 - system reserve
sda2 - Win10 installation
sda3 - where my files belong (I won't be touching this)
sda4 - this is where I plan on having my Arch linux (this partition has been my install partition for all the distros I have tried before)

Awebb

Member

Registered: 2010-05-06

Posts: 6,688

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

You explicitly asked about Grub, but here we go:

$ du -sch /boot
61M     /boot
61M     total

Grub can boot from ext4, though, so I don't see why /boot must be on the ESP. I recommend reading the following:

https://wiki.archlinux.org/index.php/GRUB#UEFI_systems
https://wiki.archlinux.org/index.php/Pa … le_layouts

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,364

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

The system reserve partition is usually not the EFI partition so it should not have relevance in any case. Are you sure your windows is installed in UEFI mode?

If it is, if you set up like recommended by Awebb above, GRUB as in the necessary bootloader part takes 133 kilobyte here.

Last edited by V1del (2020-11-03 07:49:47)

agena10

Member

Registered: 2020-10-30

Posts: 10

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

I see. Am I right in my understanding that only the files in /boot/grub goes into system reserve partition? I looked into my system reserve partition right now and it still has around 20mb of space remaining. So if I install grub at /dev/sda, then a ~13mb of grub just fits right in my current system reserve. Is that correct?

agena10

Member

Registered: 2020-10-30

Posts: 10

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

The system reserve partition is usually not the EFI partition so it should not have relevance in any case. Are you sure your windows is installed in UEFI mode?

If it is, if you set up like recommended by Awebb above, GRUB as in the necessary bootloader part takes 133 kilobyte here.

I have MBR actually. I have an Arch installation at my 2nd drive and I wanted to install it on my main drive. My current Grub for my Arch installation in my 2nd drive has 13mb. My understanding is that Grub will occupy 13mb too in my system reserve (Win10), is that correct?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,364

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

It is not, there's no reason to touch that partition at all from linux. On an MBR system you install your bootloader into the MBR section of the harddisk, which is unrelated to whatever actual partitions you have. The bootloader then either loads Windows or Linux from their actual partitions.

agena10

Member

Registered: 2020-10-30

Posts: 10

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

On an MBR system you install your bootloader into the MBR section of the harddisk, which is unrelated to whatever actual partitions you have.

So this is what I have never gotten right. I am under the impression that the bootloader is installed at the system reserve partition of Windows (in case of dual booting). I am completely wrong with my understanding of everything about this. I will do more reading from the links provided by Awebb, and look into more information.

Thank you so much guys for the help! I really appreciate it.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,364

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

https://wiki.archlinux.org/index.php/Pa … oot_Record is a good synopsis

agena10

Member

Registered: 2020-10-30

Posts: 10

Re: [SOLVED] How much space do Grub need to dual boot with Win10?

Thank you for this V1del. So this is the reason why when I check the drive with fdisk -l, the partition starts after sector 2048 of the drive, because they are reserved for the bootloader. And these sectors are hidden. I am getting there now. Thanks a lot!