There has been great hue and cry over the recently found “URL exploits” in Mac OS X. I briefly looked at this issue today. While it’s certainly a worrisome situation, in my opinion there seems to be more confusion than necessary (which amounts to a very normal situation in such cases!)
I have a few things [...]

hfsdebug can go through the volume allocation bitmap and calculate a list of free extents, along with their sizes, on a volume. Thus, you could determine the size(s) of the largest free space chunk(s) on your volume. A popular name for this appears to be “free space fragmentation”.
Although hsfdebug could quantify free space fragmentation earlier, [...]

I had been wondering for a while as to how well the combination of Panther and HFS+ stands up to fragmentation. According to Apple, there should be so little fragmentation in a typical use-case scenario that you don’t even need to worry about it. I have seen several discussions on this topic in the Mac [...]