When Grub is to be used with UEFI, it is not going to write to any MBR
of any disk. As such, it is safe to use multiple "nodev" device entries
when mirroring the ESP partition to multiple disks.
E.g.:
```
boot.loader.grub = {
enable = true;
version = 2;
zfsSupport = true;
efiSupport = true;
mirroredBoots = [
{ devices = [ "nodev" ]; path = "/boot1"; efiSysMountPoint = "/boot1"; }
{ devices = [ "nodev" ]; path = "/boot2"; efiSysMountPoint = "/boot2"; }
{ devices = [ "nodev" ]; path = "/boot3"; efiSysMountPoint = "/boot3"; }
];
};
boot.loader.efi.canTouchEfiVariables = true;
```
Fixes #18584
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.