Arch Linux

buntolo

Member

Registered: 2011-10-11

Posts: 202

Sync/backup of EFI system partition (manual RAID 1)

Since $ESP on RAID1 isn't officially supported (https://wiki.archlinux.org/index.php/EF … SP_on_RAID), I want to just use 2 different EFI partitions and sync them.

1) Which is the best way to sync 2 different EFI partitions?
2) How should I edit /etc/fstab in order to work with 2 EFI partitions?

NOTE: I use UUID for everything, I'm using device names just for the sake of readability.

My drive setup is:

/dev/sda1 EFI (fat32, mounted as /boot)
/dev/sda2 Linux RAID /dev/md1
    /dev/md1/lvosroot (ext4, mounted as /)
    /dev/md1/lvhome (ext4, mounted as /home)

/dev/sdb1 unused fat32
/dev/sdb2 Linux RAID /dev/md1
    /dev/md1/lvosroot (ext4, mounted as /)
    /dev/md1/lvhome (ext4, mounted as /home)

Using 'efibootmgr' I've added an UEFI entry "Arch Linux" for /dev/sda1; system works fine, but I want to have /dev/sda1 synced to /dev/sdb1 after every initramfs building, so that I can add an UEFI entry called "Arch Linux backup" for /dev/sdb1, in order to boot in event of /dev/sda fail.

I've doubt on which is the best practice, right now the only idea I've is to use one of the various script from "https://wiki.archlinux.org/index.php/EF … unt_points" and edit it in order to have images copied to /dev/sdb1.

The other doubt is how my /etc/fstab should looks like, right now it's like:
/dev/md1/lvosroot / ext4 erros=remount-ro 0 1
/dev/md1/lvoshome / ext4 defaults 0 2
/dev/sda1 /boot/ vfat defaults 0 2

Where and how do I add /dev/sdb1? I think that just having it on the same mountpoint as /dev/sda1 is plain bad practice.

bbus

Member

Registered: 2019-03-14

Posts: 49

Re: Sync/backup of EFI system partition (manual RAID 1)

I am not super familiar with RAID, but had an idea. First, do you build your own custom initramfs? If not, and the only time that it is built is by pacman, maybe you could create a pacman hook to copy the files from sda1 to sdb1 after pacman builds it. Or you could rsync the fallback from sda1 to sdb1 in the hook.

As to configuring it in fstab, I'm not sure. Is logic allowed, perhaps, that you could query somehow which partition called the kernel? Something to think about, anyway. Hope it helps.