====== UEFI ======

===== UEFI multi disc =====

How to handle redundant boot from multiple discs ?

Added 2 more EFI partitions (3 discs setup):

<code bash>
# Change partition 1 type to EFI on each disc:

sgdisk -t 1:EF00 -c1:efi $DISK

mkfs.fat -F 32 $DISK-PART
blkid $DISK-PART
mkdir /boot/efi0

mkdir /boot/efi1
</code>

Add new partitions to fstab:
<file ini /etc/fstab>
UUID=xxxx-xxxx  /boot/efi        vfat    umask=0077,nofail,noauto      0       1
UUID=D12D-CBBD  /boot/efi0       vfat    umask=0077,nofail,noauto      0       1
UUID=D150-1EE7  /boot/efi1       vfat    umask=0077,nofail,noauto      0       1
</file>

<file bash grub_update.sh>
#!/bin/bash -eu

DEVICES=( \
"/dev/disk/by-id/nvme-Samsung_SSD_970_EVO_Plus_500GB_Sxxxxxxxxxxxxxx,efi1" \
"/dev/disk/by-id/nvme-Samsung_SSD_970_EVO_Plus_500GB_Sxxxxxxxxxxxxxx,efi0" \
"/dev/disk/by-id/nvme-ADATA_LEGEND_710_xxxxxxxxxxxx,efi" \
)

for DEVLINE in "${DEVICES[@]}"; do

read -r DEV BOOTDIR <<< "$(echo "${DEVLINE}" | tr ',' ' ')"
grub-install --target=x86_64-efi --efi-directory=/boot/"${BOOTDIR}" "${DEV}"

done
</file>

According to [[https://wiki.debian.org/UEFI#RAID_for_the_EFI_System_Partition|RAID for the EFI System Partition]]:

<file bash /etc/grub.d/90_copy_to_boot_efi2>
#!/bin/bash

# https://wiki.debian.org/UEFI#RAID_for_the_EFI_System_Partition
set -e

# $1 - dest efi mount point
copy_efi_to() {
if mountpoint --quiet --nofollow /boot/efi; then
    mount "$1" || :
    rsync --times --recursive --delete /boot/efi/ "$1"/
    # Being FAT it is even better when not mounted, won't be damaged in case of computer crash or power outage.
    # Ref: https://forums.debian.net/viewtopic.php?p=759692&sid=ff62e9207a064b027f041d2cd0a612a4#p759692
    umount "$1"
fi
}

copy_efi_to /boot/efi0
copy_efi_to /boot/efi1
exit 0

</file>