Tonight, I uninstalled Exchange Server 2007 from a development server and was surprised to see that, after the uninstall was complete (and not without a few workarounds), only 50GB of an 80GB hard drive remained. Explorer showed 25GB free, but only 25GB had been used. Where was the remaining 30GB? Poking around the net didn’t help — most of other people’s issues revolved around System Restore and Volume Shadowing but I had disabled all of that.
Ultimately, I used a free tool called windirstat not only to find the missing space, but to delete the offending files as well. As I suspected, there were some super hidden files @ C:\Program Files\Microsoft\Exchange Server that took up nearly 30GB. I tried deleting them in Explorer (which showed me that the Exchange folder was 0kb in size) which resulted in FAIL. Windirstat, however, allowed me to right click and quickly delete the multitude of large log files.
Exchange was my issue, but your server may have another — some people mentioned anti-viruses causing issues. In any case, using windirstat will shed some light on where to find missing drive space.
Phewf! Now to install SQL Server 2008 R2 on that server…