DVD Filesystems

One long-held dream of the optical media industry (whether CD-ROM, DVD, WORM, MO, or whatever) has been platform independence. In other words, you should be able to take an optical disc that was created by a Windows machine, and read that disc on a Macintosh, or a Unix machine, or any other kind of computer with the appropriate optical media drive.

This problem of cross-platform compatibility is largely one of filesystems. For example, a computer running DOS assumes that all files have names that are 12 characters are less, while a Macintosh may permit much longer filenames. A filesystem designed to be readable by multiple operating systems much decide how to handle many such incompatibilities. A filesystem that can also be updated on the fly (not just a read-only filesystem) faces even more such issues.

After years of work, the CD-ROM industry arrived at a filesystem standard (ISO 9660) designed to work the same across multiple operating systems. It is indeed easy to make a CD-ROM disc that works with both Windows and Macintosh machines. In practice, however, it has also proven easy to create CD-ROM discs that inadvertently do not work (or do not work correctly) with all operating systems.

The DVD-ROM standard consists of two-parts: the physical specification that the disc has to conform to for the read laser to "see" the data, and the logical specification that describes how that data is to be interpreted as a filesystem. The DVD-ROM standard specifies the use of a filesystem called MicroUDF, which was a subset of a filesystem called UDF.

DVD StandardsMedia CapacityDVD