From Craig Larman
Large-scale Scrum is regular Scrum applied to large-scale development. For example, for one product group with 500 people. One key message of Scrum is to avoid a cookbook or recipe of defined process and realize that each team and each product will have to inspect and adapt their own Scrum adoption, which will evolve Sprint by Sprint. Therefore the suggestions offered here are no more than that—suggestions.
Bas Vodde and I are fortunate to work with clients so that we have been able to collect several years and many product groups of experience in adopting Scrum on multi-hundred-person large, multisite, and offshore product development. The tips suggested here reflect that experience.
One tipping point in large-scale Scrum is when it is necessary to add more support to the Product Owner. One Product Owner can directly interact with up "ten" teams (at least, the way we help set things up). Of course, there are cases where that is too high. Beyond that there is a need for a set of Area Product Owners as well. The following two framework examples for large-scale Scrum reflect this basic variation point in the organizational structure.