"4. Upgrade the host agents
- this can take a while since it'll put the hosts into maintenance mode ... so only upgrade as many as you can handle at one time (per cluster)."
Be aware on this (and any other time you place hosts in maintenance mode - deployments of you catalog items may fail during this time. When a host if going into maintenance mode vCloud still will try a clone catalog templates residing on this hosts and fail (rather than moving them to a different host and then attempting)