I am trying to migrate a small D6 site over to D7 and the Migrate/D2D modules look like they will handle most of my content. Is there any way to simply copy the D6 database over to the D7 machine and use it as a local source to migrate into the D7 database? Or, do I need to specify a path and access credentials to the mysql server on the active D6 website? Thanks.
Yes, you can source the migration from a copy of the D6 database running on the same database server as the D7 site's database. Be aware: the migrate D2D wizard will ask you for a "File prefix". In the "File prefix" field, you must specify a path to the uploaded files directory of the D6 site. Those could be a local copy also.
If in addition, you are asking how to copy a MySQL database from one server to another, that may be out-of-scope for Drupal Answers. There are tons of resources on the Internet for that—your own hosting provider may provide tools to do this. But I won't stop someone else from answering if they please. Apologies if that is not an aspect of the question posed.