question about rebuiding a gmirror on 6.1

[George Hartzell]

A friend of mine decided to take me up on my offer to help him set up
and run a freebsd-stable system (he's a photographer who's only ever
used shell accounts onto linux systems before).

We setup a gmirror using Approach 2 from
http://people.freebsd.org/~rse/mirror.

It's been up and running for a while and I just noticed that it was
running in DEGRADED mode, having failed ad4.

I had him reboot it with either ad4 or ad6 attached, and both seem to
work individually.  The data on ad4 looks "older", which makes sense
because hasn't been being updated.

Since we're not sure why it was failed in the first place and it seems
to work, we're going to hook it up and try again.

I'm nervous about whether the system will sync the newer ad6s1 data
onto ad4s1 (what I'd like to happen) or sync the ad4s1 data onto the
ad6s1 (which would suck).

Our solution is to boot off a CD with only ad4 hooked up, use gmirror
clear ad4s1 to blow away the metadata on ad4s1, then reboot with both
drives and do gmirror forget gm0s1 and gmirror insert gm0s1 ad4s1.

Am I being overly paranoid about the direction in which it'll sync the
data?

Is there a better way that I should have handled this (other than
forcing a practice run back when we got started...)?

Thanks,

g.