redeploy means put the host into maintenance mode. DRS will make the choices based off of vMotion compatibility.
1. does the host have the vCD agent installed and enabled?
2. does the host have access to the datastores required?
3. is the host not in maintenance mode?
4. does the host have access to all the required networks/distributed switches.
Think of anything that might break this. the only vMotion feature specific to vCloud director is your vCD Agent and that the host has to be enabled.