failure replacing fail hard disk

[yance at exemail.com.au]

Hi all,

I setup geom on FreeBSD following this article
http://www.onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html

With two 80 GB seagate HDD - the primary master is ad0 and secondary
master is ad2

So:
#gmirror label -v -b round-robin gm0 /dev/ad0
.
.reboot
.
#gmirror insert gm0 /dev/ad2

However, when I put ad2 as ad0 and put a fresh HDD as ad2, GEOM failed to
load.

I did run "gmirror forget gm0" command before shutting down and replacing
the HDD.

Which step would I have missed to casue this?

Kind regards,

Yance