Re: [linux-lvm] SuSE/LVM boot problem

[David Gould <dg@suse.com>]

On Wed, May 31, 2000 at 11:01:28AM +0200, Andi Kleen wrote:
> On Wed, May 03, 2000 at 09:53:26AM -0700, dgould@suse.com wrote:
> > If I have understood this, we need the following to make this
> > work (some of this may already exist):
> > 
> >  - lvm needs to provide an way for other programs to translate logical
> >    blocks to physical
> 
> A physical equivalent to FIBMAP. Not too hard to implement I think.  

Yes. That is what I meant. 
 
> >  - lvm needs to have a way of tracking/enforcing/satisfying the constraint
> >    that specified lvs need to be in the bios bootable physical area
> 
> That's pretty much impossible. How would e.g. LVM find out that the scsi
> controller of disk X does not have a boot rom? You have to trust the user there.

Fine. Trusting the user is ok, but I like the marked bootable idea to
protect against arbitrary reconfigs.

> >  - lilo needs to understand about lvm and use the lvm provided ways to
> >    get physical mappings.
> 
> That's complicated. Someone did a similar hack for RAID0, but LVM is more
> complicated than MD RAID0. Better just supply the real block numbers to lilo
> and rerun it as needed (LVM could warn about it) 

I meant only that lilo needs to call the lvm flavored FIBMAP, to get the
block numbers. That is, lilo will need a small patch.

> >  - the kernel needs to be able to reconstruct enough of the lvm
> >    descriptors to mount / at boot time.
> 
> That's handled in the initrd (lilo loads kernel + initrd, initrd contains
> LVM tools) 

Ok.

-dg

-- 
David Gould                                                 dg@suse.com
SuSE, Inc.,  580 2cd St. #210,  Oakland, CA 94607          510.628.3380
C++ : an octopus made by nailing extra legs onto a dog