On Sat, Jun 26, 2021 at 10:14 PM Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > I think it's unreliable. GRUB can write to the ESP when grubenv is on > it. And sd-boot likewise can write to the ESP as part of > https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT/ > > And the firmware itself can write to the ESP for any reason but most > commonly when cleaning up after firmware updates. Any of these events > would write to just one of the members, and involve file system > writes. So now what happens when they're assembled by mdadm as a raid, > and the two member devices have the same event count, and yet now > completely different file system states? I think it's a train wreck. It sounds like the least risky option is just manually creating more than one ESP and manually syncing them periodically as Andy Smith mentioned. (Or automatically syncing them upon every boot.) Eddie