On Oct 14, 2013, at 10:22 PM, Kun Huang <gar...@unitedstack.com> wrote:
> Hi all
>
> When searching why we couldn't use LVM or RAID on /boot, the most of answers
> are "that couldn't be support". But I would like get to know more details. In
> grub.conf file, we could use (hd0,0) to specify "root=". In another words,
> grub in stage2 actually could find data in all of disks. Is this right? If
> grub could find all partitions of all disks, what other reasons stop we find
> out information of LVM or RAID about and in disks?
Works fine with GRUB2 for the past ~2 years at least. Probably longer.
The limitation is BIOS seeing all of the disks, not a GRUB limitation. I think
there's work that needs to be done to update the GRUB LVM code when it comes to
LVM integrated raid levels 10, 5, and 6; and also thin provisioning. Except for
raid0, 1, 10, I think the rest is a bit esoteric for /boot, and is probably
more trouble than it's worth if there are device failures.
I don't actually know off hand if GRUB2's md raid code can rebuild data chunks
from parity on the fly, e.g. if there's a 1 disk failure of a raid5 array. If
not, yeah, all the more reason I'd keep /boot simple.
Chris Murphy
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