Re: [bug #39591] grub-mkconfig fails on btrfs raid

[Andrei Borzenkov]

[Adding grub-devel for wider discussion]

В Fri, 31 Jul 2015 07:13:03 +0000
Konstantin Svist <address@hidden> пишет:

> Follow-up Comment #3, bug #39591 (project grub):
> 
> GRUB_DISABLE_LINUX_UUID=true
> 
> For some reason I preferred not using UUIDs when setting it up, can't remember
> why exactly..
> 

Is it really possible to mount btrfs if only a single device is given? As I 
understand how multi-device btrfs works, to mount it you need to inform kernel 
about all (or at least enough) components. Today this is normally done by 
scanning each device during boot, feeding it to kernel and asking kernel "are 
there enough devices to attempt mount". This works only with UUID due to the 
way it is implemented in user space (udev+systemd+dracut).

Passing single individual device as root= will defeat this logic - as soon as 
device is present user space will believe everything is OK and will try to 
mount it and likely fails.

IOW - multi-device btrfs must use UUID, at least until something is changed in 
Linux boot device detection logic.

So the only question for me is - should we fail grub-mkconfig in your case or 
ignore GRUB_DISABLE_LINUX_UUID and continue? I tend to fail it with clear 
message.