Refer following doc
Migrating to Symantec Endpoint Protection 11.0 RU5
http://service1.symantec.com/support/ent-security.nsf/docid/2009090313483348?Open&seg=ent
Make sure you don't forget a good backup of the database. And don't forget to stop the service before starting the upgrade--its easy to forget that step since it is a really easy process.