On Mon Feb 04, 2008 at 12:21:40PM +0100, Keld Jørn Simonsen wrote:
> On Mon, Feb 04, 2008 at 09:17:35AM +0000, Robin Hill wrote:
> > On Mon Feb 04, 2008 at 07:34:54AM +0100, Keld Jørn Simonsen wrote:
> >
> > > I understand that lilo and grub only can boot partitions that look like
> > > a normal single-drive partition. And then I understand that a plain
> > > raid10 has a layout which is equivalent to raid1. Can such a raid10
> > > partition be used with grub or lilo for booting?
> > > And would there be any advantages in this, for example better disk
> > > utilization in the raid10 driver compared with raid?
> > >
> > A plain RAID-10 does _not_ have a layout equivalent to RAID-1 and
> > _cannot_ be used for booting (well, possibly a 2-disk RAID-10 could -
> > I'm not sure how that'd be layed out). RAID-10 uses striping as well as
> > mirroring, and the striping breaks both grub and lilo (and, AFAIK, every
> > other boot manager currently out there).
>
> Yes, it is understood that raid10,f2 uses striping, but a raid10,near=2,
> far=1 does not use striping, anfd this is what you get if you just make
> a mdadm --create /dev/md0 -l 10 -n 2 /dev/sda1 /dev/sdb1
>
Well yes, if you do a two-disk RAID-10 then (as I said above) you
probably end up with a RAID-1 (as you do with a two-disk RAID-5). I
don't see how this would work any differently (or better) than a RAID-1
though (and only serves to confuse things).
If you have more than two disks then RAID-10 will _always_ stripe (no
matter whether you use near, far or offset layout - these affect only
where the mirrored chunks are put) and grub/lilo will fail to work.
Cheers,
Robin
--
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( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
/ / ) | Little Jim says .... |
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