Bug#925591: grub-install fails on raid1+efi setup

[Vladimir K]

Installing ESP on software raid may not be a good idea, even if raid metadata is at the end of partitions.

Perhaps, a better approach would be to add procedural ESP duplication via hooks in grub and whatever else needs to write to /boot/efi (potentially debian-installer?).

Basic concept of a mechanism: use ${PRIMARY_ESP_MOUNTPOINT}.${NUMBER} as location for ESP duplicates, like /boot/efi.1, /boot/efi.2, etc...
After writing to /boot/efi, also check fs, fstab for expecded duplicate paths, sync contents to all found duplicates, then add duplicated entries via efibootmgr for each device.