CD file system (CDFS)

CDFS is a file system designed for Microsoft Windows 95 that supports the reading of compact discs.

What is CDFS (CD file system)?

A file system designed for Microsoft Windows 95 that supports the reading of compact discs. A CD file system (CDFS) provides the same kind of file and directory management for CD-ROM devices that the file allocation table (FAT) or NTFS file systems do for hard disks.

CDFS is also implemented on the Windows 98, Windows NT, and Windows 2000 platforms.

How it works

On Windows 95 and Windows 98, CDFS uses a 32-bit protected-mode driver that supports the ISO 9660 CD file system standards. This 32-bit driver replaces the 16-bit real-mode MSCDEX driver that was used in the legacy 16-bit Windows and MS-DOS operating system platforms. In Windows 95 and Windows 98, the file system driver that supports CDFS is called cdfs.vxd, while in Windows NT and Windows 2000, it is called cdfs.sys. CDFS is optimized for reading compact discs that have a standard data block size of 2048 bytes (2 KB). The implementation of CDFS includes a dynamic, protected-mode cache pool for caching CD-ROM data to improve read performance. This allows CDFS to read ahead to ensure that playback of multimedia content from CDs is smooth and seamless.


CDFS on Windows NT, Windows 2000, Windows 95 OSR2, and Windows 98 includes a number of enhancements over the original version of CDFS for Windows 95, such as

  • CD-XA support for optimized reading of MPEG video CDs having larger block sizes of 2352 bytes.
  • Auto-Run, which allows applications on CDs to start immediately when the CD is inserted into the drive. To do this, the operating system reads the autorun.inf file that is stored in the root of the directory structure on the CD.

Using Services for Macintosh, you can create a Macintosh-accessible volume on a CDFS volume by following the same steps you would use to make an NTFS volume accessible to Macintosh clients. Of course, the CDFS volume has one difference: it is read-only.

CDFS is an acronym that stands for Compact Disk File System.