close 909533 thanks Hi,
thank you for your report. EFI system partitions (ESP) are partitions with a specific partition type, regardless of the filesystem within (usually fat32). Linux MD depends on having the partitions of type Linux raid, so mdadm cannot be used for this use case. The "correct" way to mirror your ESPs is to have a grub hook that takes care of this. Currently, debian doesn't have this out-of-the-box included in the grub2 packages, but Ubuntu has a 'grub-multi-install' that takes care of that. As an alternative to this, if you search the internet, you'll also find several "rsync hooks" for grub2 to do this in another way. Regards, Daniel
