Search Server 2010 has several search topology components. You can scale out these components to multiple servers to increase performance, capacity, and availability of the search system.
You can modify a search topology only if you selected the Server Farm installation option when you installed Microsoft Search Server 2010.
Microsoft Search Server 2010 Express is an entry-level enterprise search solution that has limited scalability. In Search Server 2010 Express, the topology components of each Search service application must be on one server. Although it is possible to add topology components on that server, in most cases it is not useful. For information about scalable solutions for enterprise search in Microsoft SharePoint 2010 Products, see Technical diagrams (SharePoint Server 2010).
The topics in this section describe the purpose of the search topology components and the ways to add or remove search topology components in a server farm.