Do you know what is on your hard drive?

Up till now, Windows Explorer was my main (and only) tool for finding information about the contents of a hard drive. It served me reasonably well except in a few situations.

One situation is tallying the total size of a folder. The Windows Explorer on Win 2000 can quite handily tell you the size of a partition, and of an individual file. However, when it comes to folders, the size that it reports only includes the files that are immediately in that folder. If the folder has subfolders, you need to bring up the Properties of the parent folder, and then it will slowly tally up the total size. I don't use Win XP. So, I can't say if the Explorer on Win XP was any improvement.

Another situation is when your disk is filling up, and you need to search and destroy the big files that are eating up disk space. If Explorer is all you have, you have a lot of work to do.

A great complement to Windows Explorer is windirstat. windirstat is a disk usage statistics viewer and cleanup tool for Windows.

When you fire up windirstat, it prompts you for the drive or folder that you want analyzed. The results are displayed in 3 views: the Explorer-like view, the extension view which summarizes the data by the file extensions, and the treemap view where each file is graphically depicted as a block in a color-coded map.

Using the color-coded treemap, you can quickly and visually pick out the biggest files. Because the views are linked, you can click on a block in the treemap, and the corresponding file will be highlighted in the Explorer view. This is a quick way to identify the biggest files on your hard drive. Now, you can choose to delete the file from the Explorer view.

Another example of how the views are linked is that you can click on an extension in the extension view, and all blocks in the treemap with that file extension will be highlighted.

I was happy to know that windirstat supports not only ASCII but also Unicode filenames. That is a big plus for those who use non-English languages.

For tools that can potentially traverse your entire hard drive, one naturally is concerned about its stability and scalability.

Regarding stability, the project is classified as Production/Stable in the SourceForge system. From the web comments, and our own experience (albeit short), there is nothing that suggests to me otherwise.

Regarding scalability, I ran windirstat against all my partitiions (37G of actual data). It took about 3 minutes on a slow Duron (800MHz, 256M) machine to analyze all 120,000 files. The TreeMap was amazingly usable, even with that many files, to give a visual representation of the disk space allocation.

I like the tool, not only because it does what it is supposed to do, but also it was fun while I was doing it.