Device Driver
The piece of software which is used to interface an optical disc drive, CD / DVD recorder drive or SCSI library robotics to the host computer. This software converts generalized instructions to the specific commands used by the device.

Directory Cache
An index of all the files in an XFS. The directory cache is stored on hard disk, and contains the name and attributes of every file in an XFS. It is used for all directory listing and look up operations.

Dirty File
A file in the File Cache which has been modified, and hence differs from the version of file (if any) on backing store. A dirty file has to be flushed from the file cache.

DVD (Digital Versatile Disc)
A newer, large-capacity disc, DVD-ROM is much like a large CD-ROM. DVD-R is a recordable DVD-ROM. This is the next generation compact disc technology, offering a vast capacity improvement. Initially capacity is set at 4.7Gb, but this will change with the introduction of multi-layer discs, capacity will double. DVD discs should be formatted with the UDF file system.

DVD-RAM
DVD-RAM is a fully re-writable disc, very similar to optical disc, but complying with DVD standards. Unlike optical drives, DVD-RAM drives can read DVD-ROM and CD-ROM discs. DVD-RAM drives will read and write to a 4.7GB DVD-RAM disc, read and write-once to a 3.9GB DVD-R disc, and read a 4.7GB/8.5GB DVD-ROM disc. Also, it is expected that a DVD-RAM disc will be readable on both the DVD-R and DVD-ROM drives. DVD discs should be formatted with the UDF file system.

Extended Architecture
Also called XA. A CD standard, which supports types of CDs other than standard audio CDs and CD-ROMs. Used with CD-ROM Mode 2.

File Attributes
Information stored with a file. This typically includes file type, ownership, access times and access permissions. Archimedia also stores other information, such as the number of the subsystem containing the file, and whether the file is in the file cache.

File Cache
A temporary store used by Archimedia for files, to improve performance. Files are normally accessed using the file cache, since this is much faster than using the backing store.

Flush
The action of copying a dirty file from the file cache to the backing store.