Re: [PATCH] Use new sb type

[Tim Southerwood <ts@dionic.net>]

David Greaves wrote:
> Peter Rabbitson wrote:
>> David Greaves wrote:
>>> Jan Engelhardt wrote:
>>>> This makes 1.0 the default sb type for new arrays.
>>>>
>>> IIRC there was a discussion a while back on renaming mdadm options
>>> (google "Time
>>> to  deprecate old RAID formats?") and the superblocks to emphasise the
>>> location
>>> and data structure. Would it be good to introduce the new names at the
>>> same time
>>> as changing the default format/on-disk-location?
>>>
>>> David
>> Also wasn't the concession to make 1.1 default instead of 1.0 ?
>>
> IIRC Doug Leford did some digging wrt lilo + grub and found that 1.1 and 1.2
> wouldn't work with them. I'd have to review the thread though...
> 
> David
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

For what it's worth, that was my finding too. -e 0.9+1.0 are fine with
GRUB, but  1.1 an 1.2 won't work under the filesystem that contains
/boot, at least with GRUB 1.x (I haven't used LILO for some time nor
have I tried the development GRUB 2).

The reason IIRC boils down to the fact that GRUB 1 isn't MD aware, and
the only reason one can "get away" with using it on a RAID 1 setup at
all is that the constituent devices present the same data as the
composite MD device, from the start.

Putting an MD SB at/near the beginning of the device breaks this case
and GRUB 1 doesn't know how to deal with it.

Cheers
Tim