Gmirror dump device does not exist?

[Nick Pavlica]

All,
  I have just set up a FBSD6.0 server configured with gmirror/raid1
using two SATA drives ad4 & ad6 according to these instructions:

                 http://www.onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html

  Everything is functioning properly with the exception of a boot
warning that indicates that a dump device does not exist.  I'm sure
that I just missed something simple during the setup procedure.  Does
anyone have the quick fix for this?

My fstab:

# Device                      Mountpoint      FStype    Options       
 Dump    Pass#
/dev/mirror/gm0s1b      none               swap       sw              
  0       0
/dev/mirror/gm0s1a      /                      ufs          rw        
        1       1
/dev/mirror/gm0s1e      /tmp                 ufs         rw           
      2       2
/dev/mirror/gm0s1f       /usr                  ufs          rw        
        2       2
/dev/mirror/gm0s1d      /var                 ufs          rw          
      2       2
/dev/acd0                   /cdrom             cd9660  ro,noauto       0       0

Thanks!
-Nick