Re: RAID-6 support in kernel?

[Allan Sandfeld]

On Monday 03 June 2002 10:57, Kasper Dupont wrote:
> Roy Sigurd Karlsbakk wrote:
> > > > RAID-6 layout: http://www.acnc.com/04_01_06.html
> > >
> > > If it is supposed to survive two arbitrary disk failures something is
> > > wrong with that figure. They store 12 logical sectors in 20 physical
> > > sectors across 4 drives. With two lost disks there are 10 physical
> > > sectors left from which we want to reconstruct 12 logical sectors.
> > > That is impossible.
> >
> > Might be the diagram is wrong.
>
> Could be the case, so until I find another description I will
> still not know how RAID-6 works.
>
It's not just the diagram, the theory is wrong. You need to use at least log2 
n+1 disks for partition if you want to handle any two lost/borked disks. (16 
disks would give 11x diskspace).