Unlike the real world, in your computer space is not infinite. While you can approximate infinite space with gargantuan disks, at some point however far away it may be, the disk will be too small. At this point it would be real handy to profile the disk’s file system by disk usage. One tool I find particularly handy and use time and time again for this purpose is ‘TreeSize Free’. The software is made by JAM Software, and is the light version of TreeSize Professional. See the screenshot below for an example report.