In this article I will show how to move documents using SharePoint 2013 workflows. This approach works well for SharePoint 2013 on premise deployment as well as for SharePoint Online in Office 365. I will implement archival workflow as a proof of concept, which moves documents from one document library to another, but you can modify it a little and use to copy documents or folders cross-site.
As you probably know, you can store many documents in the SharePoint document libraries. For SharePoint 2013 it is 30 000 000 per library. However, there is another limit which spoils all the fun, it is list view threshold 5 000 documents or list items. There are also another limit, like security scope limit, which doesn’t allow to have more than 50 000 security scopes. Roughly speaking it is amount of documents or folders with unique permissions. You can find full list of list and library limits on technet.com.