Microsoft® SQL Server 2012 Unleashed

Using Filegroups

Filegroups allow you to align certain database objects with specific data files. Tables, indexes, and large object (LOB) data can be assigned to a filegroup. A filegroup can be associated with one or more data files. The alignment of data and indexes to filegroups can provide performance benefits and improve manageability. Each database has at least one filegroup, called the primary filegroup. This filegroup, by default, contains the primary data file and any other secondary data files that have not been specifically aligned with another filegroup. Any database object that you create without specifying a filegroup is created in the primary filegroup.

Additional filegroups can be created and aligned with secondary data files. ...