Hi! Why don't you just use "du -B 4096 -sh /path/to/fs" vs. "du -B 16384 -sh ..."? Subtracting both results is the overhead of the one vs. the other. But to answer your request for the formula, its: blocks = (long)((file_size + block_size - 1) / block_size) occupied_size = blocks * block_size But this does not tell you the real on-disk occupation because it takes the logical file size of the files into account. But files may be sparse or compressed which sheds a complete different light on the problem. I'd go with "du" command because it takes this into account. Regards, Kai Sandra Schlichting <littlesandra88@xxxxxxxxx> schrieb: > Hi all, > > When having a non-btrfs fs and want to migrate to btrfs, it is hard to > know which sector size to choose in terms of disk utilization and > speed. > > So I would like to make a script that scans the non-btrfs fs's > directory structure to find all file sizes and calculate how much > space these would take on btrfs 4k and 16k sector size. > > Can anyone help me with a formulae to calculate this for a file? > > It doesn't have to be exact, just enough to make a decision between 4k and > 16k. > > Best regards, > Sandra > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
