[CentOS] one-shot raid mirror to remote?

I have a filesystem on a RAID1 partition created with a 'missing'
mirror so I can periodically sync with an external drive for
backup.  Now I'd like to move the contents to a different machine
that has a matching partition with minimal downtime.  Is it
possible to export the new partition via iscsi or an nbd device
so that the old system will sync to it over the network allowing
an unmount of the old to be followed by an immediate mount of the
new mirror with a very short time when it will be unavailable?

-- 
  Les Mikesell
   lesmikesell at gmail.com