The following is a list of critical data stored on your system. Used in this context, the term "data" is a more inclusive term than one that defines simple application data. Critical data can include:

Data also refers other possible data storage requirements, which can include:

Other critical elements stored on your disk include:

If this information is already stored on your system, you know or you can determine the amount of data you are storing.

If you are putting together a new system, planning for these data storage elements can be a difficult task. You need to a complete understanding of the application and its potential hardware requirements. One of the first things you must know is how much data you intend to store in each table of your database, and which tables will grow and which are static. See the database storage calculations discussed in the Calculating database storage requirements.