[effie]

> One downside to storing these images on the (FAT) EFI System Partition is it is not possible to make it part of a software RAID device, so if the device the ESP is on dies suddenly, the boot fails

It is possible to make ESP part of MDRAID array of level 1 with metadata v1. True, the boot starts with single disk and only later Linux activates the array. So if your boot fails before that happens, reboot and try the other disk.

Or alternatively, don't set up MDRAID array for ESP, just have the ESP mirrored on all disks.

[iam-TJ]

"don't set up MDRAID array for ESP, just have the ESP mirrored on all disks. "

Isn't that the entire point of utilising MD RAID-1 in the first place?

I've done as you suggest in years gone by with either metadata v0.9 or v1.0 (not v1.1 or v1.2) where the metadata is not at the start of the block device and therefore does not confuse a non-MDRAID-aware firmware or other OS.

[effie]

> I've done as you suggest in years gone by with either metadata v0.9 or v1.0

Then why did you wrote

> it is not possible to make it part of a software RAID device

You are saying it is both not possible and that you've done it.

[iam-TJ]

It is NOT possible to have the UEFI access the RAID device so that if one of the mirrors is broken it can continue to boot in degraded mode.

It requires manual intervention of a knowledgable person to boot a UEFI system into the default OS if the ESP is broken or missing.

[effie]

OK now I get what you mean. In that case, one can reboot and select the other non-broken disk and the system will boot, with some hiccups due to degraded array, but it will boot.