Semantic knowledge is system specific; therefore, we discuss D-GRAID design and implementation for two widely differing file systems: Linux ext2  and Microsoft VFAT  file system. Inclusion of VFAT represents a significant contribution compared to previous research, which operated solely underneath UNIX file systems.
The ext2 file system is an intellectual descendant of the Berkeley Fast File System (FFS) . The disk is split into a set of block groups, akin to cylinder groups in FFS, each of which contains bitmaps to track inode and data block allocation, inode blocks, and data blocks. Most information about a file, including size and block pointers, are found in the file's inode.
The VFAT file system descends from the world of PC operating systems. In this paper, we consider the Linux VFAT implementation of FAT-32, although our work is general and applies to other variants. VFAT operations are centered around the eponymous file allocation table, which contains an entry for each allocatable block in the file system. These entries are used to locate the blocks of a file, in a linked-list fashion, e.g., if a file's first block is at address b, one can look in entry b of the FAT to find the next block of the file, and so forth. An entry can also hold an end-of-file marker or a setting that indicates the block is free. Unlike UNIX file systems, where most information about a file is found in its inode, a VFAT file system spreads this information across the FAT itself and the directory entries; the FAT is used to track which blocks belong to the file, whereas the directory entry contains information like size, permission, and type information.