At the shell prompt, I begin making the file systems on my partitions. Linux supports types of file systems other than ext2. Mounting a partition means attaching it to the linux file system. Some facts about file systems and fragmentation Disk space is administered by the operating system in units of blocks and fragments of blocks. In ext2, fragments and blocks have to be of the same size, so we can limit our discussion to blocks.
Files come in any size.
They don't end on block boundaries. So with every file a part of the last block of every file is wasted. Assuming that file sizes are random, there is approximately a half block of waste for each file on your disk. You can guess the number of files on your disk by the number of allocated inodes on a disk. Had I chosen a block size of 4 KB, I would have lost 4 times this space.