Triple boot : how many Efi partitions I need?

John

6/17/24, 7:04 PM

I have 2ssd's : Ssd1 will have windows 10 Ssd2 will have windows 10 and Ubuntu

How many Efi partitions do I need? Also what size?

0 + 7

boot

uefi

oldfred

6/17/24, 9:22 PM

You only need one. I typically prefer to have one per drive, but Ubuntu defaults to installing to first drive's ESP. First drive's ESP is defined by UEFI. Often suggestion, if wanting to use a second drive's ESP is to remove first drive. Some can turn off or disable drive in UEFI( settings. It may work to remove boot,esp flags from first drive's ESP, also. Windows used to use 100MB, but default now be 200MB. Some suggest as large as 525MB, but unless using many installs or SystemD boot, you will not use that space. A single install of Windows & Ubuntu fits in the 100MB with space left over.

John

6/18/24, 4:26 AM

Thank you Alfred. In the case that the first drive fails, can an Efi partition with necessary boot files be created on the second one for the remaining windows+Linux? I'm thinking to have some redundancy in case one ssd fails.

oldfred

6/18/24, 2:04 PM

That is exactly why I have an ESP on every drive. And often install boot loaders for installs on that drive into that drive's ESP. You can even do that with Windows if second install of Windows does not see first install. If ESP exists on second drive, you also can use your Windows repair/recovery flash drive to reinstall Windows boot files or Ubuntu live installer to reinstall grub. I have mutltiple flash drives & now an external SSD (much better than flash drive) to install boot loaders. You can have multiple entries in UEFI all saying "ubuntu" but with boot to different installs.

oldfred

6/18/24, 2:08 PM

One advantage of two Windows boot entries is then grub will find the two ESPs with Windows boot files & add them to grub menu. So you can directly boot both Windows from grub. Windows has to have bitlocker & fast start up off for grub to boot it. You also have to turn os-prober on at least once to find entries. But best to copy entries into 40_custom and turn os-prober off. https://ubuntuforums.org/showthread.php?t=2478842 & http://askubuntu.com/questions/653101/boot-repair-windows-not-listed

John

6/18/24, 3:51 PM

Until now I had Efi partitions made automatically, but I could select only the windows installations from starting menu. In order to boot Ubuntu I had to press f11 in order to select the boot menu. The configuration was similar, on one ssd windows 10 and efi, on other ssd windows 10 and Ubuntu. I don't remember if I had an efi partition on the 2nd ssd as I swapped it with a larger one recently. So I don't know now how to make it in order to have all 3 installations on the starting menu. I'm thinking to wipe out every partition on both ssd's , then create 2 efi on both ssds

oldfred

6/18/24, 5:53 PM

You can always add an ESP, it normally is first partition, but only needs to be in the first 2TB?, I think. Windows always adds to first installs BCD. But if not seen then it creates a new BCD. Grub cannot see into BCD, but if two separate sets of Windows boot files grub can boot either one. You can manually create entries with efibootmgr to directly boot from UEFI and edit grub menu items when in 40_custom. Only HP requires you to change boot order in UEFI settings as it somehow does not accept boot order changes with efibootmgr.

John

6/19/24, 9:30 AM

I installed all 3 systems with one EFI and I have option to boot only from the windows ones at system startup. I have to select bootloader with F11 in order to boot from Linux. Not a big hassle anyway, it would of been nicer if I had all 3 boot options but I can live with that. In the meantime I made backup to windows partitions and Efi, in case the ssd with efi fails, I can restore it to other drive.

Elon Musk

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EN: Triple boot : how many Efi partitions I need?

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