PLEASE READBEFORE UPGRADING. Your target site alias must be set up correctly before you begin.
The new home for site-upgrade drush command, which streamlines the major version upgrade process for Drupal. Currently, only upgrades from Drupal 6 to Drupal 7 are supported. See https://www.acquia.com/blog/use-drush-upgrade-drupal-6-drupal-7.
The Drush site upgrade command will walk you through the major upgrade process, help you select new projects where necessary, and run content migrate to update your cck fields. Please be sure to read the documentation and take note of any special conditions you may encounter. See the README.txt file for more information.
drush dl drush_sup
If your site uses Features, see.
If your site has shared database tables, see.
For best results, use Drush Site Upgrade 7.x-2.x-beta2 or later on Drush 6 or later.