clearing Vinum configurations

[aarong]

I've been toying with Vinum extensively these past few weeks, on 4.8, 
and I've yet to come across a way to effectively and *completely* clear 
a Vinum configuration. After creating a configuration, Vinum stores the 
configuration on the drive or drives and resetconfig does not clear 
that written config. Case in point, after reinstalling FreeBSD on a 
primary drive, Vinum started up and read the previous installs 
configuration from the second drive which had not been formatted. On 
another install, I tried zeroing out the 265 Vinum sectors found 16 
sectors in on the primary drive, but was greeting with a "missing 
operating system" on reboot.

Two questions:

1) why doesn't resetnconfig clear all the configurations, including the 
ones written to Vinum drives?
2) why doesn't dd if=/dev/zero of=/dev/da0 seek=16 count=265 work? 
What's in those 265 sectors that I can't touch?

Regards,
-aarong