Content analysis is the cornerstone of your content management initiative. It includes careful review of the documents and objects that exist and that would help to define scope of your project.
The main purpose of content analysis is to provide data that is critical to the development of a solid information architecture. It helps you to reveal patterns and relationships within content and metadata than can be used on to better structure, organize, and provide access to that content. It will also help to configure your content management system accordingly. It will help you in the design phase when you begin coming up with content types and metadata. It also provides valuable input into the broader design of organization, labeling, navigation, and searching systems.
I recommend to my clients to conduct content analysis in the form of detailed audit. Early in the research phase, a high-level content survey could be a useful tool for learning about the scope and nature of content. Later in the process, a content audit or inventory would produce a roadmap for the project and will facilitate an organized approach to authoring and managing of content.