some studies have shown that for multimedia applications, a larger block size improves throughput (e.g. 256kb blocks). For large media files, the waste of an average 128kb per file is insignificant (over several megabytes to many hundred mb or indeed GB). But, for smaller files (typically occupied by configuration files or small system binaries) a smaller block size saves more space (4k block for 100byte file).

ReiserFS goes for something slightly different allowing several files to share a single block. I am unsure if the extra effort involved in implementing this is worth it, or the slower access times that reiser reports for allowing this.

Maybe different allocation groups could have different block sizes? maybe there could be some kind of block-size migration system? or would the overhead not be worth it? Could it be one of those “maintenance” tasks that you run every month/year? How often does the average usage of a disk change that we’d need something like this?