Keep an eye on your content database sizes

When you're putting together a plan for Web applications and content databses in your environment, consider your expected usage patterns and how you expect your content databases to grow.
As a general rule of thumb, Microsoft recommends against growing content databases to larger than 200GB unless the content in the database meets specific non-collaborative usage criteria, such as that which is associated with single-site repositories and archives.
Databases that grow larger than the 200GB limit may cause performance degradation due to locking; they also represent a challenge from a backup and restore perspective.