Re: grub2/grub-pc install not possible on mdadm

[Chris Murphy]

On Feb 28, 2012, at 12:42 PM, Stefan Priebe wrote:

> Am 28.02.2012 19:38, schrieb Stefan /*St0fF*/ Hübner:
> 
>>> But the device still does not boot. Installing grub to sda / sdb does
>>> not work either as they do not contain any partition table. What's wrong
>>> here?
>> 
>> That's probably it ...
>> 
>> The BIOS cannot guess that there may be a partition table inside a raid
>> about which it doesn't know anything...
> 
> That's why a grub-install --no-floppy /dev/sda and grub-install --no-floppy 
> /dev/sdb should install grub on these MBRs and the rest should be handles by 
> the mdraid1x grub module. If i use 0.90 metadata this works fine and grub 
> installs without any errors on sda and sdb using the mdraid09 module.

The partition table should be outside of RAID, and define the member devices 
(and partitions) that make up the array. But inside the RAID, other than RAID 
1, the file system itself is obscured and GRUB probably can't find it's various 
modules in e.g. /boot/grub2/

Seems like core.img needs to already have mdraid1x.mod already baked into it, 
in order for GRUB2 to understand RAID, and find the rest of its modules to 
load. But my understanding is that to boot off RAID, it had to be RAID1. I 
didn't think it was possible to have /boot on say RAID 0, 5, or 6 but I could 
be confused. The manual isn't exactly clear what RAID levels mdraid1x.mod 
supports.

Chris Murphy