If you are attempting to perform a migration from an existing 6.16 site, be SURE to back up your database as well as your files. Fortunately for me, I did. I decided to see what the latest release was about and installed it in a subdirectory on my account. Install went fine. Backed up my 6.16 database and files. After following all directions and having all modules installed, all plugins set up and registered, and testing my new 7 installation I began the data migration. Did a lot of checking see more prior to this in the forums and blogs to see what others had encountered. Selected the Profiles as instructed and started the migration. I need to state here that my 6.16 database is modded in a number af areas, but profiles table isn't too much different. Okay, profiles showing started. After a while, I figured it should be done. Still showing in progress. I wait for a while longer and know that it shouldn't take this long. Still running. I checked my database for 7 and no profiles beyond the admin I initially set up. I go back to my actual 6.16 site and suddenly all members are standard and no photos for anyone. I stopped the migration and took a look at the 6.16 profiles table. ALL the profile ID's have been changed there. New numbers starting with 5454 where they were originally started at number 1. I go to my sql backup and select my profiles table and recreate the original profiles table. Then had to clear the cache folder (I just renamed it and created a new empty cache folder. My members are now back to their original settings and photos are back.
Anyone contemplating migrating their data should be aware that it MAY not go as planned and have a backup ready to go. I'll have to research this a bit more, but it DOES state that a 6.16 to 7 RC3 data migration is possible. The errors I encountered in mine according to my cron job errors notices seem to be related to the migration script looking for the D7 RC3 tables in my 6.16 database. not sure why.