JP MensMar 16

Configuring a RAID1 array on Linux is widely (and I think sometimes even correctly) described on the internets, as is how to mark a drive as faulty.

What nobody discusses is whether and how to mirror the EPS partition, how to detect / be alerted when a disk becomes faulty, or how to actually boot from the other drive if all one has are two drives in a simple configuration.

On to the other hand, and to be fair, internet search has become so shit it's pathetic.

Show threadKevin P. Fleming
@jpmens I use this for keeping the content of the ESPs in sync: https://github.com/gregory-lee-bartholomew/bootsync
GitHub - gregory-lee-bartholomew/bootsync: Keep ESPs synchronized on mirrored-disk systems

Keep ESPs synchronized on mirrored-disk systems. Contribute to gregory-lee-bartholomew/bootsync development by creating an account on GitHub.

GitHub
Mar 16 at 10:15amWeb
Show threadzhenechMar 16
@kevin @jpmens I think @youam was saying the other day, you can just do a "real" RAID with metadata format 1.0 so it puts the stuff at the *end* of the partition and UEFI is not confused.
Show threadKevin P. FlemingMar 16
@zhenech @jpmens @youam That's an interesting idea!
Show threadUli MartensMar 16
@kevin @zhenech @jpmens yup, it boils down to: `mdadm --create /dev/md/efiboot --raid-devices=2 --level=1 --bitmap=internal --name=efiboot /dev/sdX2 /dev/sdY2 --metadata=1.0`
Show threadJP MensMar 16
@youam @kevin @zhenech so, if you can forgive my ignorance, AFTER that I would do some grub magic to actually write into /dev/md/efiboot with the correct data which MD would then RAID1, since MD cannot know which partition currently contains the real deal.
Show threadzhenechMar 16
@jpmens @youam @kevin huh? You mount /dev/md/efiboot on /boot/EFI and your OS will use that to store the bootloader. If that's an existing system, you'd have to move the old contents of /boot/EFI there once, so the whole deal becomes: backup /boot/EFI, do mdadm magic, mkfs.vfat /dev/md/efiboot, mount /dev/md/efiboot /boot/EFI, restore backup, edit /etc/fstab - I am sure you can do this
Show threadJP MensMar 16

@zhenech @youam @kevin I was assuming an existing system with an ESP into which grub had installed its stuff.

I also assumed, that if I create an MD on top of that ESP device (and its counterpart on disk 2), that I'd have to grub-install again.

Thanks for clarifying and, yes, I ought to manage that

Show threadzhenechMar 16
@jpmens @youam @kevin the nice thing with UEFI is that you don't have to "hide" Grub in some obscure section of the MBR but only copy a few files with the right names to a VFAT formatted disk.
Show threadKevin P. FlemingMar 16
@zhenech @jpmens @youam Indeed, this is a huge improvement. I use systemd-boot instead of GRUB but the technique should be the same.
Show threadJames Just JamesMar 16

@zhenech @jpmens @youam @kevin If I'm understanding all of this correctly, you've got an elegant way to reliably boot off an effective software raid1 EFI boot drive.

I'd like to build this engineering into the open source #mgmtconfig provisioning system and am happy to pay you for your time to walk me through it and get it right. Lmk if you'd have a moment to chat!