Ablative WORM
Under this system a laser is used to burn a pit into a recording layer which can be used to represent a change between the digital 1 and 0 states. This can later be read back by using a laser and detecting the change in reflectivity at the pit.

Allocation Algorithm
An algorithm for determining which subsystem is to be used for storing a file, when it is flushed from the file cache.

Alloy WORM
Under this system the recording layer consists of three dual-element alloys which, when heated by the laser, change into a single new four-element alloy. This change can be detected and read by the drive to recover the data.

Autochanger
Another name for a Jukebox or Library.

Backing Store
The collection of discs which make up the permanent storage of the XFS. Archimedia automatically migrates files between backing store and the file cache.

Block, Disk/Disc Block or Logical Block
Another term for a sector; the smallest addressable unit on an optical disc, DVD or CD.

Burning
The actual recording of the CD / DVD. Also known as mastering or cutting the disc.

Caching
A way of providing fast data retrieval without having to refer to the actual files located elsewhere within the system, maybe residing on a slow jukebox.

CCW WORM (Continuous Composite WORM)
Magneto Optical media is used in this system, with media that has been specially prepared at manufacture to inform the drive to only allow one single write to a sector on the disc.

CD-ROM (Compact Disc - ReadOnly)
Compact Disc Read Only Memory - the name given to a Compact Disc containing computer data.

CD-RW (Compact Disc - ReWritable)
The media is based on phase change technology capable of storing up to 700 MB of data on one disc. The ability to read the disc requires a reader to be compatible with 'multireaded' specification drives.

CD Image
An 'image' of an ISO9660 or UDF file system, which gets copied to the CD. This image is stored on a hard disk partition, which is C:\cdimage.img by default for Windows and /cdimage.img for Solaris.

Clean File
A file in the file cache for which an exact copy exists on backing store. A clean file can be purged from the file cache to create space.

Control Files
The collection of files used by Archimedia for storing overall information about an XFS. These are normally stored in directories under C:\Program Files\K-PAR\xfs in Windows or /var/kpar/xfs in Solaris.