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I have three disks on my computer. One HDD, two SSD's.

ON HDD - it's only free space now. In the past I had Ubuntu there.

On SSD1 - there is Windows + EFI System Partition (which -probably- is where GRUB is installed. In the past, used this partition to dual-boot the old Linux install on the HDD with the Windows one)

Now, I bought a new SSD and installed Ubuntu. Let's call it SSD2.

ON SSD2 - Ubuntu only (not specific EFI System Partition) + partition for windows files.

On the install, in the "Device for bootloader installation" option I've chosen:

"/dev/nvme0n1p4" > format: ext4 Same partition that I've installed the whole system, not a specific EFI System Partition.

So here I have two questions. 1- do I have two GRUB's installed? I mean, if I remove the SSD1, will I be able to boot into the Linux only using SSD2? 2- Is there any practical consequences to install the bootloader on the system partition (like i did on SSD2) instead of some specific EFI Partition (like I Did on SSD1)?

Did some research, and was still a bit confused, however, got some commands that can be useful to clarify my current situation to you:

sudo fdisk -l

Disk /dev/nvme0n1 (SSD2 - New): 232,91 GiB
Device             Start       End   Sectors   Size Type
/dev/nvme0n1p1        34     32767     32734    16M Microsoft reserved
/dev/nvme0n1p2     32768 253513727 253480960 120,9G Microsoft basic data
/dev/nvme0n1p4 254513152 488396799 233883648 111,5G Linux filesystem

Disk /dev/nvme1n1 (SSD1 - Old): 119,25 GiB
Device             Start       End   Sectors  Size Type
/dev/nvme1n1p1      2048 249659391 249657344  119G Microsoft basic data
/dev/nvme1n1p2 249659392 250068991    409600  200M EFI System

lsblk

sda (HDD)           8:0    0 931,5G  0 disk 
└─sda6        8:6    0   7,2G  0 part 
nvme0n1 (SS2 - New)     259:0    0 232,9G  0 disk 
├─nvme0n1p1 259:1    0    16M  0 part 
├─nvme0n1p2 259:2    0 120,9G  0 part 
└─nvme0n1p4 259:3    0 111,5G  0 part /
nvme1n1 (SSD1 - OLD)     259:4    0 119,2G  0 disk 
├─nvme1n1p1 259:5    0   119G  0 part 
└─nvme1n1p2 259:6    0   200M  0 part /boot/efi

sudo efibootmgr -v

BootCurrent: 0000
Timeout: 0 seconds
BootOrder: 0000,0002,2001,2002,2003
Boot0000* ubuntu    HD(2,GPT,giant_number)/File(\EFI\ubuntu\shimx64.efi)RC
Boot0002* Windows Boot Manager  HD(2,GPT,giant_number)/File(\EFI\Microsoft\Boot\bootmgfw.efi)WINDOWS.........x...B.C.D.O.B.J.E.C.T.= (giant_number)......
Boot2001* EFI USB Device    RC
Boot2002* EFI DVD/CDROM RC
digolira2
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  • If the giant_number in your efibootmgr list for Windows is same as Ubuntu, then both are using the same ESP. That is the partition unique GUID or partUUID. You can see partUUID: lsblk -e 7 -o name,fstype,size,fsused,label,partlabel,mountpoint,uuid,partuuid I prefer to have an ESP on every drive just to allocate the space and maybe use for a second install or backup location for ESP, or so I can have unique entries. But ubiquity defaults to ESP on first drive. Old bug. https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379 – oldfred Sep 14 '21 at 14:39
  • See this answer for a solution to the bug @oldfred Also see this and this answer. – user68186 Sep 14 '21 at 16:56
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    @user68186 Bug report has several work arounds. If installing you can unmount incorrect ESP & mount correct in middle of install (#55). Or Tim Richardson's suggestion (#49) of turning off ESP flag on other ESP's. Or your links on those & disconnecting or in UEFI settings disabling all other drives. – oldfred Sep 14 '21 at 18:23
  • Thanks @oldfred :) – user68186 Sep 14 '21 at 18:28

1 Answers1

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I can see only one instance of grub installed on your system and this instance is installed to your EFI System Partition /dev/nvme1n1p2 (SSD1 - OLD).

If you remove the drive which holds the EFI System Partition you will be unable to boot either OS on this machine.

Installing an instance of Grub to the OS-partition does only make sense in legacy-mode, but not in UEFI-mode. In UEFI-mode the installer will try to install Grub to an existing ESP (the installer searches itself for a valid ESP) and ignores the choice of bootloader location you made.

mook765
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