I recently installed ubuntu alongside windows.

I partitioned the drives manually and read that you need 1 efi(esp) per disk and was afraid of overriding windows files on the original. Another thing is I have 2 drives /dev/sda(hdd) and /dev/sdb(ssd/ windows). The efi was located on /dev/sda while windows install is on /dev/sdb.

I created another efi in /dev/sda and installed ubuntu, so now I have 2 esp on that drive and seems to be running ok, but accoring to This I should have only one.

Do you think this will conflict in the future and Should I:

(A) Remove ubuntu/extra efi partition(if so is there any precautions to take to not mess up UEFI)

(B) Keep as is

  • If you can boot both OS with no problems leave it alone (IMHO if it is not broken dont fix it). – Panther Oct 28 '17 at 17:59
  • Thanks for the input dude, that was my first thought. I wanna get a consensus though because I feel like It may come back to haunt me in some unforseen way – Dominucius Oct 28 '17 at 18:15
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    The EFI specification imposes no limit on the number of ESPs that may be present on a computer or on a hard disk. superuser.com/questions/688617/… Some computer vendors may implement firmware that violates the UEFI-standard, but your questions indicates that this is not the case for your machine. I'd tend to follow @Panther 's advice. – mook765 Oct 29 '17 at 5:20
  • @mook765 you should post that as an answer – Panther Oct 29 '17 at 12:50
  • @moop765 I couldn't find any explanation was to why it was not recommended to use more than one. That should give me enough peace of mind, thank you sir and also thanks Panther – Dominucius Oct 29 '17 at 15:05

I'm the author of the answer on SuperUser that mook765 quoted. I'm therefore going to cut-and-paste part of that answer, and make some edits to it....

The EFI specification imposes no limit on the number of ESPs that may be present on a computer or on a hard disk; you could have dozens of them if you wanted to, and that would be fine from the EFI's perspective. Unfortunately, Microsoft is not so flexible; Windows officially supports just one ESP per disk (maybe per computer; I'm a bit foggy on that detail). I don't know about Windows 8 or later, but the Windows 7 installer will flake out if it sees more than one ESP on a disk; the installation will proceed part of the way and then fail. (At least, that's what it's done in my tests.) That said, if you create a second ESP after installing Windows, Windows will continue to boot and operate correctly, at least as far as I've seen. (I can't promise that it won't misbehave if you use some particular feature, though.)

Overall, then, in a multi-boot environment, I recommend restricting yourself to one ESP. I also recommend making it rather large -- 550MiB is my usual recommendation, for assorted technical reasons having to do with rare bugs and FAT sizes. That said, if you've got an existing installation with a smaller ESP, or with multiple ESPs, it's probably fine to just stick with it. In either case, Linux and Windows can share a single ESP just fine. I do, however, recommend backing it up early and often -- definitely back it up before installing a new OS. Because the ESP holds your boot loaders, an accidental erasure of it will render your computer unbootable.

If you need to re-install Windows, it may be necessary to "hide" the non-Windows ESP by changing its type code. You can do this with gdisk in Ubuntu with the t command. (Try setting it to 8300, which is the code for a Linux filesystem.) You'll also need to use w to save the changes. Don't do this now, though; do it only if it becomes necessary in the future.

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  • Thanks Rod, I appreciate the in-depth explanation. I'm taking note and will backup and reformat my machine. I had a feeling that there might be some wierd interactions, but all seems well for the time being. – Dominucius Nov 3 '17 at 21:14

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