When creating a new NTFS partition one is asked to choose a cluster size. The default size is 4k but one can choose a smaller sizes, too. 512 bytes is the smallest.
The smaller size leads to wasted space reduction. Each file occupies 1 or more clusters depending on file size. If the file size can be divided by the cluster size then no space is wasted by default. Otherwise only some part of the last cluster will store file data and remaining space will be wasted. On average it's about half of the cluster size per file. Considering that a typical partition stores tens of thousands of files 265 vs. 2k per file sounds like a big deal for me.
I always choose 512 bytes to reduce the amount of wasted space but I believe that there might be some negative effects of using smaller clusters. Otherwise 512 bytes would be used by default. What are those drawbacks?