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#1 2025-12-07 21:12:16

jselb
Member
Registered: 2025-12-07
Posts: 3

GRUB doesn't find my W10 installation - dual booting on separate disks

I installed W10 first on a 500GB ssd (/dev/sda). Everything was working fine.

I then installed Arch on my nvme (/dev/nvme0n1). I had to disable secure boot for it to work. However now when I reset GRUB only recognizes the arch install. I did not change anything on the ssd where W10 was installed. The only change I can think of was disabling secure boot.

Output of fdisk -l

Disk /dev/sda: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk model: CT500MX500SSD1  
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: DC955BE9-014C-4895-9D7A-1997165C7923

Device     Start       End   Sectors   Size Type
/dev/sda1   2048     34815     32768    16M Microsoft reserved
/dev/sda2  34816 976773119 976738304 465.7G Microsoft basic data


Disk /dev/nvme0n1: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: WDS100T3X0C-00SJG0                      
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: BC8FEE9B-5DFF-4083-B3A2-9409E1EF5F05

Device           Start        End    Sectors  Size Type
/dev/nvme0n1p1    2048    1050623    1048576  512M EFI System
/dev/nvme0n1p2 1050624 1953523711 1952473088  931G Linux filesystem

output of efibootmgr -v

BootCurrent: 0003
Timeout: 2 seconds
BootOrder: 0003,0000,0004
Boot0000* rEFInd Boot Manager	HD(1,GPT,1be5ddb1-3114-47c9-af22-e0f6534b1074,0x800,0x100000)/\EFI\refind\refind_x64.efi
      dp: 04 01 2a 00 01 00 00 00 00 08 00 00 00 00 00 00 00 00 10 00 00 00 00 00 b1 dd e5 1b 14 31 c9 47 af 22 e0 f6 53 4b 10 74 02 02 / 04 04 3a 00 5c 00 45 00 46 00 49 00 5c 00 72 00 65 00 66 00 69 00 6e 00 64 00 5c 00 72 00 65 00 66 00 69 00 6e 00 64 00 5f 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 00 00 / 7f ff 04 00
Boot0003* GRUB	HD(1,GPT,1be5ddb1-3114-47c9-af22-e0f6534b1074,0x800,0x100000)/\EFI\GRUB\grubx64.efi
      dp: 04 01 2a 00 01 00 00 00 00 08 00 00 00 00 00 00 00 00 10 00 00 00 00 00 b1 dd e5 1b 14 31 c9 47 af 22 e0 f6 53 4b 10 74 02 02 / 04 04 30 00 5c 00 45 00 46 00 49 00 5c 00 47 00 52 00 55 00 42 00 5c 00 67 00 72 00 75 00 62 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 00 00 / 7f ff 04 00

output of parted -l

Model: ATA CT500MX500SSD1 (scsi)
Disk /dev/sda: 500GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name                          Flags
 1      1049kB  17.8MB  16.8MB               Microsoft reserved partition  msftres, no_automount
 2      17.8MB  500GB   500GB   ntfs         Basic data partition          msftdata

Model: WDS100T3X0C-00SJG0 (nvme)
Disk /dev/nvme0n1: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name  Flags
 1      1049kB  538MB   537MB   fat32              boot, esp
 2      538MB   1000GB  1000GB  ext4

I tried using the built in W10 install repair on the windows drive and it errored out.
I installed ntfs-3g and os-prober.
I  uncommented "GRUB_DISABLE_OS_PROBER=false" in /etc/default/grub and reran sudo grub-mkconfig -o /boot/grub/grub.cfg

What else am I missing? Thanks!

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#2 2025-12-07 21:34:02

euromatlox
Member
Registered: 2017-02-10
Posts: 149

Re: GRUB doesn't find my W10 installation - dual booting on separate disks

So you are using both rEFInd and Grub boot managers ? Usual way is having only one boot manager, so I guess this is 'out of my mind' a little bit.

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#3 2025-12-07 21:44:03

jselb
Member
Registered: 2025-12-07
Posts: 3

Re: GRUB doesn't find my W10 installation - dual booting on separate disks

I removed rEFInd. I was trying to see if it was a grub issue but here's the current output:

BootCurrent: 0003
Timeout: 2 seconds
BootOrder: 0003
Boot0003* GRUB	HD(1,GPT,1be5ddb1-3114-47c9-af22-e0f6534b1074,0x800,0x100000)/\EFI\GRUB\grubx64.efi
      dp: 04 01 2a 00 01 00 00 00 00 08 00 00 00 00 00 00 00 00 10 00 00 00 00 00 b1 dd e5 1b 14 31 c9 47 af 22 e0 f6 53 4b 10 74 02 02 / 04 04 30 00 5c 00 45 00 46 00 49 00 5c 00 47 00 52 00 55 00 42 00 5c 00 67 00 72 00 75 00 62 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 00 00 / 7f ff 04 00

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#4 2025-12-08 01:21:49

jselb
Member
Registered: 2025-12-07
Posts: 3

Re: GRUB doesn't find my W10 installation - dual booting on separate disks

i reinstalled W10 and this resolved itself. Not sure why it broke initially

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