Avantis CD/DVD Server Technology Backgrounder

Network Attached Storage

Avantis CD/DVD servers are designed around the ‘plug and play‘ principle of network attached storage (NAS). The CD/DVD server connects directly to a hub or switch on the network and operates independently of other servers on the network. The CD/DVD server can still be accessed even if other servers are down. Avantis CD/DVD servers can be set up in minutes and need no screen or keyboard to install on the network.


Hard disk technology

Avantis pioneered the use of hard disk technology to store and distribute multimedia CD and DVD information. Called Adaptive CD Imaging™, this approach provides rapid access to CD-ROM and DVD information by creating and storing images of CDs on fast hard disk drives.

Unlike optical CD-ROM drives, towers and jukeboxes, hard disk based CD server appliances provide superb levels of performance, concurrency and reliability, allowing many users to access CD and DVD information simultaneously. Data access from a CD is much slower than from a hard disk drive. The fastest CD-ROM drives have an average access time of about 100ms, compared to less than 10ms for hard disk drives.

Data transfer rates are used to describe the reading speed of the CD-ROM drive. The original CD-ROM drives had a data transfer rate of 150 KB/sec but since the computer can handle data at ever higher speeds, manufacturers are now offering 4X, 24X, 40X and higher speed drives. However, this is of little benefit when CD-ROMs are shared over a network using a standard CD tower or jukebox as data throughput from the CD-ROM drives is let down by poor access times. With a hard disk based approach, higher sustainable data throughput rates are achievable even when concurrent access is required.

Comparative throughput of data for Optical CD Tower vs Avantis Hard Disk Based Server

KB/sec = amount of data read in a second. Avantis make these calculations based on an arbitrary 64KB to be read on each read request

Multimedia Virtual Drive™ Technology

Avantis' unique client software creates virtual CD/DVD drives on the workstation which emulate real CD/DVD drives. CDs are then accessed from the user's workstation just as they would be from real local CD-ROM or DVD drives, but with the advantage that each workstation can have multiple CD/DVD drives. CDs can then be launched automatically from shortcut icons on the desktop, or dragged and dropped onto virtual drives in the Avantis CD Explorer. This approach, developed by Avantis, is known as Multimedia Virtual Drive™ technology, and is the only system that offers compatibility with ALL formats of CD and DVD

No other CD-ROM sharing solution uses this technology or has the ability to fully support multimedia CD-ROMs or DVDs. These virtual drives are able to recognise formats such as Audio-CD, DVD Video and even CDs or DVDs that cannot normally be networked or copied.

Format	Description	Supported
ISO 9660	ISO 9660 is the most common type of CD-ROM. It is used to store computer data as defined by the International Standard ISO 9660. Avantis CD servers can store ISO 9660 CDs very efficiently as only the data portion of the CD's sectors are stored.
Microsoft Joliet	Allows long filenames on Windows systems
Rock Ridge	Allows long filenames on UNIX/MAC systems
High Sierra	High Sierra is an early CD format used for storing computer data. It has been superseded by ISO 9660 and has become a rare format.
CD-i (CD Interactive)	CD-i contains video films and computer programs for CD-i players.
CD-ROM XA	CD-ROM-XA is a family of CD types that have an ISO 9660 type file system. CD-ROM-XA is a general type of CD and is often used as one of its subtypes e.g. PHOTO CD.
CD-i Bridge	CD-i Bridge is a format of CD that unifies aspects of CD-ROM XA and CD-i. It is a abstract type of CD and is normally used as one of its subtypes eg. VIDEO CD.
Photo CD	Photo CD is a type of CD-i Bridge CD used for storing photographic images as defined by Kodak and Philips.
Video CD	Video CD is a type of CD-i Bridge CD used for storing video films.
Super Video CD	An extension of Video CD that supports DVD type video.
CD Digital Audio (CD-DA)	CD Digital Audio is the original audio CD format as used in hi-fi CD players.
ISO 9660 with Audio Tracks	ISO 9660 with Audio Tracks is a hybrid CD. It contains an ISO 9660 CD followed by CD-DA tracks.
Enhanced Music CD	In this format data tracks follow audio tracks. This is more compatible with stand alone audio CD players than the other hybrid CD type.
Packet CD	A type of CD-ROM that has been created incrementally. Uses UDF file system to allow efficient updates on CD-R and CD-RW.
DVD-ROM	This is a high capacity format of CD-ROM.
DVD-Video	This is a DVD-ROM that contains high quality video tracks. These may be encrypted. OpenCD does not currently read DVDs protected using CSS (Content Scrambling System).
DVD-Audio	This is a DVD-ROM that contains high quality sound tracks.
General Type	General Type is a special type of CD defined by Avantis. It is provided as a safety net for CDs that OpenCD fails to recognise. It is also used as the type for File System image creations.

The Avantis CD/DVD Compatibility Guarantee

Avantis servers offer compatibility with ALL formats of CD and DVD. This means that we support all known CD and DVD formats including:

• In-house mastered CDs
• Many copy protected formats
• CD and DVD formats that cannot normally be networked or copied