DiskView

Checking disk space means, on the one hand knowing how much left you have to deposit files of interest. On the other hand, experienced individuals might need to thoroughly analyze the structure of drives, and this operation can easily be performed with the help of specialized applications like DiskView.

Can be used on the go

You can go ahead and take the application for a spin as soon as download is done, because there's no setup involved. Not only does this save a great deal of time and effort, but it makes it possible to have the application launched from a thumb drive on other computers, without leaving any traces because registry entries are not altered in the process.
The visual design is pretty intuitive, even though there's not really a great deal of effort invested into aesthetics, not that visuals are the center of attention here. The window can be resized for better view and analysis of clusters, with a large space to show a zoomed region, as well as a horizontal display. Upper toolbar is used to trigger general functions, while drive selection is done from the lower section.

Scan options and exporting

In case you want to analyze removable storage devices, it's best to plug them in first. You select the target drive from a drop-down menu. Entire partitions are scanned, with no option to select a specific folder. You can, however, specify a file as reference and only it and related items in the cluster are scanned.
In order to obtain maximum performance you might want to cease all other activities during the scan process. Time varies according to the size of the target drive, as well as the number of files and folders. Preview regions update in real-time, with colors used to differentiate health status of clusters. Selection immediately shows highlighted file. You're able to zoom, and even export the result to file.

On an ending note

Taking everything into consideration, we can state that DiskView is not your average disk space analyzer, and is best used for technical inspection whenever you consider the HDD is failing. It's able to scan both fixed and removable drives, with intuitive display of scanned clusters, and possibility to save reports.