Data blocks, also called storage blocks, contain the rest of the space that is allocated to the file system. The size of these data blocks is determined when a file system is created. By default, data blocks are allocated in two sizes: an 8-Kbyte logical block size, and a 1-Kbyte fragment size.
For a regular file, the data blocks contain the contents of the file. For a directory, the data blocks contain entries that give the inode number and the file name of the files in the directory.