We have good expertise and experience in upgrading drupal6 sites to drupal7 latest version. We have experience in upgrading very complex drupal6 sites to drupal7. So far we have upgraded many drupal6 websites to drupal7 website, but 2 of them were very difficult and had lot of contents, tables in them.
1) http://www.greenbuildingadvisor.com/ -- It was in drupal6. When you open this site you will see this is huge site in terms of functionality and contents. There were 16 custom modules developed in order to meet the particular requirements. More than 1GB of database with 300 tables in them. Here is the statistics of site in Drupal6-
- Custom Modules - 16
- Database Size - 1GB
- Number of Tables- more than 500
- Contents - very huge
We took following steps in upgrading process.
Green Building Advisor Upgrade Process
- Updated Drupal core from 6.13 to 6.28.
- Updated all modules to recommended version.
- Keep backup for updated drupal 6.
- Logged in with administrator user (user id =1).
- Changed the site in maintenance mode.
- Changed all theme (enabled and administration) to Garland.
- Disabled all the non-core modules one by one.
- Removed default settings file from default directory (sites/default).
- Removed all core files except the ?sites? directory.
- Download the latest Drupal 7 (Drupal 7.22).
- Copied the all core files from Drupal 7.
- Made ?settings.php? file writable.
- Run the update script (Update.php).
- After update script completed keep backup (database and files).
- Downloaded latest cck module (drupal7) and put it in modules directory.
- Enable cck and content migrate module on module page.
- Browse to the fields migrate page and checked Unavailable fields.
- Migrated all available fields.
- Changed three fields widget type from database.
Table name: - content_node_field_instance
Field name Widget Type Changed Widget Type
field_blog_multi_images bgimagefield_widget filefield_widget
field_prod_image bgimagefield_widget filefield_widget
field_product_review_images bgimagefield_widget filefield_widget
It was really a complex process to change this website from Drupal6 to Drupal7. We enjoyed working on this websites and hope we would be doing some more complex upgrades in near future.