I had to create an EFI partition to install ubuntu 18.04. Now I want to create another boot on the same HD with 18.04 again. Do I need to create another EFI partition?

  • So you will have two instances of Ubuntu 18.04 on one HDD? – Pilot6 Mar 18 at 17:15
  • yes, @Pilot6 . The reason is irrelevant, but "My old 18.04 partition is going to fail soon due to bad block and Im moving to another one. As HP limits the number of partitions I can have, I care about creating new partitions". – Vitor Abella Mar 18 at 18:22
  • HP doesn't limit the number of partitions. MBR maybe does. – Pilot6 Mar 18 at 18:24
  • @VitorAbella: If you're having accumulating bad blocks and impending data loss, you need to replace the entire disk, not just a single partition. Reserved blocks are shared across the whole drive. – Ben Voigt Mar 19 at 2:26
  • As always, I'd suggest reading this as a primer on UEFI. And then from a Ubuntu perspective you can either have multiple GRUBs managed by EFI, or one GRUB with muliple OSes managed by GRUB. But only ever the one ESP. – Bob Mar 19 at 2:46

No, you only need one EFI partition. My dual-boot system shares the one partition between Windows and Ubuntu.

You can see it here with all the goofy Windows partitions. (My / partition is on a different physical drive)

enter image description here

  • so, when I install i choose my ubuntu efi partition that I already created? – Vitor Abella Mar 18 at 17:08
  • That's correct. – Pilot6 Mar 18 at 17:08
  • I've only done it once. I created a new EFI partition, and the installer ignored it and used the existing Windows one. – Organic Marble Mar 18 at 17:09
  • @OrganicMarble That's not an EFI problem per se. Some computer's BIOSes always boot Windows if a Windows EFI binary is present, regardless of the user's boot choices. This is broken behavior, but since nearly all of the affected computers are several years old now, they're unlikely to be fixed. – Michael Hampton Mar 19 at 1:49
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    @OrganicMarble Oh, OK, I see what you mean. It doesn't really matter though, you can have as many EFI partitions as you want. If it bothers you, or you need the disk to be removable, you can move the relevant files from one EFI partition to the other (though you might have to tweak the boot order in the BIOS afterward). – Michael Hampton Mar 19 at 2:00

You need only one EFI partition for a computer in general.

No matter how many OS you have.

You may need multiple EFI partitions only in some special cases when you swap disks, change boot device in UEFI, etc.

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