gmirror array not unmounting at shutdown

[rloefgren at forethought.net]

I have a mirror with two 500GB SATA drives for storage. The system is on a 
gmirror of two 18GB SCSIs. the SATA mirror mounts under /u2 and is in 
fstab. If I reboot, when the machine comes back up I get a notice that /u2 
was not unmounted properly. I go into single user, unmount /u2 and do a 
fsck on /dev/mirror/datas1d. It usually finds some issues and corrects 
them. Sooner or later it's going to fail at the repair.

I thought that by having the array in fstab that the system would take it 
down properly upon a reboot, but that doesn't appear to be the case. Where 
can I put a "sync ; umount /u2" where it will take place late enough that 
/u2 actually will unmount? I've looked at rc.shutdown but can't find a 
place where such a line actually seems to be executed.

thx,

r