[Plugin: W3 Total Cache] Media Library Import Tool

The media library import tool is for old or “messy” WordPress installations which have attachments (images etc in posts) all over their web server or hot links to 3rd party sites instead of properly using the media library.

The tool will scan your posts for the cases above and copy them to your media library, update your posts to use the link addresses and produce an .htaccess file of redirects so search engines (etc) can find the files in their new location.

You should backup your database before doing this, although I’ve never seen the operation fail.