8.0 install fails to create filesystem ("unable to find device node")

[Vitaly Magerya]

Kevin Oberman wrote:
>> The setup tries to create filesystem and fails with this message:
>>
>>     Unable to find device node for /dev/ad0s1b in /dev!
> 
> Are you doing a 'W'rite in the labeling tools? I'm guess that you are
> not, but I wanted to be sure. You don't want to.

Nope, no write.

> You say that you are doing the default partitions. If so, the 'b'
> partition should be swap. It should not get 'newfs'ed. No file system
> needed (or wanted) there. This tells me that something was wrong in the
> partition setup if it THINKS that there is a need to newfs partition
> 'b'. 

Yes, ad0s1b is the swap, but I think it fails before doing newfs.
"Writing partition information to ad0" is the last message I see before
the error occurs, no newfs popups occur.

>> Aside from debug messages, there's this on second VT:
>>
>>     GEOM: ad0: geometry does not match label (255h,63s != 16h,63s).
> 
> This is a known issue, but cosmetic in almost all cases.

OK, good.

> I suspect that you are doing something wrong, but it's hard to figure
> out just what it might be.

Anything I can do to see what's the problem?