update to 8.0-RELEASE --> partition gone

[Ben Morrow]

Quoth Marcel Moolenaar <xcllnt at mac.com>:
> On Dec 15, 2009, at 4:08 PM, Ben Morrow wrote:
> > Quoth Marcel Moolenaar <xcllnt at mac.com>:
> >> On Dec 15, 2009, at 2:20 PM, Steven Friedrich wrote:
> >>>> 
> >>> FreeBSD 8.0 no longer supports "dangerously dedicated" disks.
> >> 
> >> This is not true. The problem is that sysinstall creates an invalid
> >> "dangerously dedicated" disk, as demonstrated by doing:
<snip>
> > 
> > Are you able to clarify exactly what is no longer working in 8?
> 
> Everything is working, but behaviour has changed for invalid
> disks.

Right. However, if I were to take a system that worked with 7.x and
upgrade, and found that the disks were no longer detected, I would
consider that to be 'not working' :).

> Invalid disks are disks with conflicting partitioning
> information. In FreeBSD 8.x the behaviour is deterministic
> and for the broken dangerously dedicated disks that sysinstall
> creates this means that we use the partition information in
> the BSD disklabel. In FreeBSD 7.x this could come from either
> the MBR or the BSD disklabel, with the MBR the more common
> scenario.

OK, so this is all actually about a bug in sysinstall. It might be nice
if the UPDATING entry mentioned this: as it stands it is not clear this
doesn't affect people who created proper disklabels by hand (including
the obligatory dd to wipe out old MBR labels before starting).

> > If I currently have a working ad2{b,c,d,e}, will they
> > be picked up by 8, or would I have to repartition slightly smaller with
> > a useless MBR slice in front?
> 
> Yes, if you have ad2a and not ad2s1a, then you have a
> proper dangerously dedicated disk and FreeBSD 8.x will
> work correctly with your disk.

Thank you for explaining.

Ben