What is the relationship between unit allocation size and filesystem overhead? Specifically, I have a 250gig external drive, NTFS, default allocation size, and once formatted, Win7 tells me I have 232 gig of usable space. Fine. I've essentially got 18 gig of overhead. If I change my allocation size down to 512 bytes, will my overhead increase?

I know that there will be a performance hit due to the larger number of block seeks and that defragging will be longer and more important with the smaller blocks. Question is, will it affect the size of the overhead?

Thanks,

Moxieman

Reckon the best way to find out is ... to find out.

Most likely, making the allocation-size smaller will cause the filesystem data structures to become larger, thus consuming more space, because now the system has to keep track of more allocation-units.

That's what I thought. My question was whether anyone had previously done the experiment or the math, and figured out how much of an increase there would be.

So, "just do it," and let us know.