On Tue, May 20, 2003 at 07:00:31PM +0100, David Laight wrote:
> 
> > I seem to have a few more days' space to experiment in.  I'll
> > probably revert off RAID for production, but I'm now curious.
> > Anyone think I can actually boot off the combined pair?  I can't
> > quite see how, but I'm quite clueless in this case.
> 
> It is possible that the NetBSD install procedure overwrote the raid
> configuration that was on the disk - so it reverted to a normal disk.
> 
It's a selection in the boot sequence, much as SCSI controllers
offer when they start up.  The choice is RAID 0/1 (striping and
mirroring, from unschooled memory), the irksome thing is that "none"
is not an option, if you disable the facility, the controller
disappears.  A newer version of the hardware seems able to provide
two additional EIDE controllers instead.

Now, how this affects NetBSD boot is another question.  But as I
read it, the disks are just images, the controller with software
help presents them as one device.  The bootstrap loader and kernel
both must provide the software understanding.

Now, in mirror mode, each disk would need to be normal, so booting
off either image would work, if tempting fate.  But in striping
mode, this is not going to work.

> It is also possible that everything 'just worked' (at least to some
> extend) and the offset the kernel has to use to access the mirrored
> disk was ok.
> 
Hm, not out of the question.  I did leave the traditional 62 sectors
free (or is it 63?).

> However I'm not sure that the i386 boot code (as installed by sysinst)
> can possibly work for these raid sets.  The i386 /usr/mdec/installboot
> copies disk sector numbers into the bootstrap area, since the sector
> numbers used by the bios and those used by the kernel now differ this
> is unlikely to be correct.
> 
Installboot is a mystery.  If you're responsible for the new version,
will you please give us a pointer to the man pages for it?  And
can we get rid of the confusion/ambiguity.  I'm still reeling from
no longer being able to produce a netboot diskette.  The sad bit
is that I can't find a version of NetBSD to do it, and I have 1.3.2,
1.4.2, 1.5.2, 1.6 and 1.6.1 installed :-(

Hm, I think the switch to ELF has totally thrown the old version.

> It is quite possible that the new i386 boot code I've written will
> work, but I suspect there will by an 'off by 64' error in it somewhere!
> I don't have a raid test system.
> 
Happy to help you refine this in the next few days.  I doubt that
I'll be able to twist a supplier's arm to lend me the hardware to
play once I leave the client premises where I need to deploy a
working system with the hardware I'm using now.

> The setup is easy just:
> use /usr/sbin/installboot to copy usr/mdec/bootxx_ffsv1 into the boot area,
> and copy /usr/mdec/biosboot to /boot.
> 
I presume this is on -current.  It will take me some time, but I'm
certainly interested.

> If it doesn't work I'll fix it at the end of next week..
> 
Too late, but I'll help as long as I can.

++L