Re: md extension to support booting from raid whole disks.

[Daniel Reurich <daniel@centurion.net.nz>]

> > Could we do this better using containers and snia's ddf in intels matrix
> > (or our own) metadata to define the data areas and this way create a
> > raid1 container at the start of the disks and use 1.0 format superblock
> > and metadata at the end of the drive (as long as this doesn't mess with
> > the metadata.  
> > 
> > This would solve the syncing of boot sectors because it would be done as
> > part of normal raid 1.  Hot add would simply be a matter of adding
> > members to the container.  The only issue I can see is whether you are
> > able to hot resize the data areas in containers as part of the grow
> > feature, or would we have to do a metadata tweak to redefine the size of
> > data areas.
> 
> While it might be possible to do something vaguely like this, I don't
> want to.
> 
Is it already possible to do with mdadm v3?

BTW, I'm not talking about just raiding the boot sector, but a raid1
volume with a filesystem for /boot with the embedded bootsector at the
start of it.  This means that for every member disk that includes
the /boot volume we have a mirror.

The description I got about ddf|matrix containers led me to believe this
was a robust way to do this.  

What's the point in supporting ddf|matrix containers if we can't create
the data areas within them to suit particular use cases like this?  

If we could/can then nothing further needs to be done to md/mdadm to
allow me to implement my preferred boot solution.

> don't bother having a raid1 there that is never read
> and hardly ever written..
????
It's read every time we boot!

I guess I've failed to communicate what I'm after effectively! :(

-- 
Daniel Reurich

Centurion Computer Technology (2005) Ltd
Ph 021 797 722