We've been operating Ubuntu servers for a long time and for most of that time we've booted them through traditional MBR BIOS boots. Initially it was entirely through MBR and then later it was still mostly through MBR (somewhat depending on who installed a particular server; my co-workers are more tolerant of UEFI than I am). But when we built the 24.04 version of our customized install media, my co-worker wound up making it UEFI only, and so for the past two years all of our 24.04 machines have been UEFI (with us switching BIOSes on old servers into UEFI mode as we updated them). The headline news is that it's gone okay, more or less as you'd expect and hope by now.

All of our servers have mirrored system disks, and the one UEFI thing we haven't really had to deal with so far is fixing Ubuntu's UEFI boot disk redundancy stuff after one disk fails . I think we know how to do it in theory but we haven't had to go through it in practice. It will probably work out okay but it does make me a bit nervous, along with the related issue that the Ubuntu installer makes it hard to be consistent about which disk your ' /boot/efi ' filesystem comes from.

(In the installer, /boot/efi winds up on the first disk that you set as the boot device, but the disks aren't always presented in order so you can do this on 'the first disk' in the installer and discover that the first disk it listed was /dev/sdb.)

The Ubuntu 24.04 default bootloader is GRUB, so that's what we've wound up with even though as a UEFI-only environment we could in theory use simpler ones, such as systemd-boot . I'm not particularly enthused about GRUB but in practice it does what we want, which is to reliably boot our servers, and it has the huge benefit that it's actively supported by Ubuntu (okay, Canonical) so they're going to make sure it works right, including with their UEFI disk redundancy stuff . If Ubuntu switches default UEFI bootloaders in their server installs, I expect we'll follow along.

(I don't know if Canonical has any plans to switch away from GRUB to something else. I suspect that they'll stick with GRUB for as long as they support MBR booting, which I suspect will be a while, especially as people look more and more likely to hold on to old hardware for much longer than normally expected.)

PS: One reason I'm writing this down is that I've been unenthused about UEFI for a long time, so I'm not sure I would have predicted our lack of troubles in advance. So I'm going to admit it, UEFI has been actually okay. And in its favour, UEFI has regularized some things that used to be pretty odd in the MBR BIOS era .

(I'm still not happy about the UEFI non-story around redundant system disks, but I've accepted that hacks like the Ubuntu approach are the best we're going to get. I don't know what distributions such as Fedora are doing here; my Fedora machines are MBR based and staying that way until the hardware gets replaced, which on current trends won't be any time soon.)