The disk space function displays the total amount of information that you're able to have on the cloud website hosting server at one time. With a desktop computer, for example, this is the total size of one hdd or the full volume of all hard disks in case that the computer has more than one. The same way that the space on a PC is shared between installed applications, docs, your music and so on, the server storage space is usually shared between site files, databases and e-mail messages. Every file, folder or email message will take a little disk space on your server, so you should take into account quite a few factors, not only the size of the files which you upload. For instance, receiving large e-mail attachments or running a script-driven website where the user-generated data is kept in a database may also affect the space you use.