- May 2012 - One year have past since I initially wrote this article. Upgrading these days from Drupal 6 to 7 have become easier, safer, and a lot less nerve wrecking, though it will never become a cakewalk.
- May 2015 - Started writing a longer series using Migrate and Migrate D2D.
- May 2015 - Cleaned up language a corrected grammar erros.
To migrate or upgrade?
As writing do I still have a few more complex sites running on Drupal 6. Knowing these sites, their complexity, and all existing glue code, a fast and easy upgrade will be hard pull off. It might be easier for complex sites to only migrate the content using modules like migrate and migrate_d2d.
A data migration
- Do a clean Drupal 7 installation.
- Build basic needed content types and configurations.
- Recreate the theme in D7 or port you existing CSS/SASS styles.
Then migrate your content by using modules like http://drupal.org/project/feeds, or for even more flexibility and power http://drupal.org/project/migrate. I'll promise do a blog post of a more complex Drupal 6 to 7 migration as soon as my remaining sites are running Drupal 7.