On 21/01/2023 13:32, Pascal Hambourg wrote:

Back on topic, if you mean Windows+Linux dual boot, it seems unlikely to 
me that this can be achieved with Linux software RAID, because Windows 
does not support it and Windows software RAID usually works on whole 
drives.
If you mean Linux dual-boot, you do not need multiple boot loaders, one 
single boot loader can boot all Linux systems.

Given that this all started with *MIRRORING* EFI partitions, I think 
you've lost the thread ...

I'm fully in agreement that - if we want to keep our EFI partitions in 
sync - then doing so when the partition is updated is the best TIME (not 
place) to do it. (Which is why mirroring makes sense.)

It's just that - as soon as you bring multiple OSes (of any sort) into 
it - this ceases to be a practical solution.

Even something as simple as using a single boot loader with multiple 
linux distros is fraught with problems. I did exactly that, and the 
automated grub updater left *ALL* OSes unbootable. I was forced to boot 
with an emergency CD and edit grub.cfg by hand to get even one linux 
back, so I could then try to fix the rest.

THERE'S TOO MANY WAYS TO SKIN THIS CAT and trying to automate it will in 
almost all cases lead to tears :-(

Cheers,
Wol