Upgrade Lotus Traveler from 8.5.3 to 9

Hi all,

any suggestions for upgrading Lotus Traveler Server from 8.5.3 to 9 version? I need to make attention to some particular step? My environment consist in three domino server in HADR (with DB2) and Domino Cluster on S.O. Windows 2008 R2.

Thanks in advice.

Alessandro