Migrate-d2d UI - Where does sites/default/files source content go? I am setting up a dedicated development environment on my home LAN where I can work on a Drupal 6 to Drupal 7 migration. So far, I have a clean Centos 7, LAMP stack, and Drupal 7 install and have configured periodic file and image backups to my local NAS. The D6 drupal database has been imported and connected in settings.php and appears to be recognized by the migrate_D2D UI.

What I am unclear about is how to migrate the D6 site's downloadable file content and images under sites/default/files.  Although the D6 site is live and remote, I was thinking about copying relevant portions of the sites/default/files path over to the development system, but I don't know where to put it or how to reference it as a data source in the migration process.  

I would assume that the format or field mapping conventions for content in sites/default/files is different between Drupal 6 and 7 and source and destination content must remain separate, but I am not sure about this.  So can anyone advise me as to the best approach for incorporating this D6 content into D7?  I would be happy to either copy the content over or read it remotely from the live site if this is supported.  Thanks.

19 hours later:

I haven't resolved this yet so let me ask my question again with a couple of visual aids.  Here is the file tree of the sites/default/files section from my legacy Drupal 6 website:



Here is the file tree of the sites/default/files section from the clean install of the Drupal 7 website I am trying to migrate into:



My question is where migrate_d2d wants me to put the legacy (source) Drupal 6 files.  Do I put it inside the new sites/default/files tree or somewhere separate from where the post-migration Drupal 7 files will be?

Thanks again.
I'll post this as a preliminary answer, but please feel free to comment with better suggestions.

Step 4 (Files) of the migrate_d2d UI asks for path where the source files can be found.  I took the conservative approach and uploaded the legacy sites/default/files file system to a separate source directory on the development server, but I don't see why you couldn't directly import the legacy file content into the sites/default/files directory on the destination server.

At least this seems to work so far.