DVD-RAM
Encyclopedia
DVD-RAM is a disc specification presented in 1996 by the DVD Forum
, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computer
s as well as camcorder
s and personal video recorders since 1998.
s. Its competitors are DVD-RW
and DVD+RW
. DVD-RAM technology provides excellent data integrity, data retention and damage protection through a number of mechanisms and properties. Therefore, DVD-RAM is perceived by some people to be better than the other DVD technologies for traditional computer usage tasks such as general data storage, and especially data backup and archival. The Mount Rainier Format
standard and SecurDisc for DVD+/-RW (which also works on DVD-RAM, CD-R, and CD-RW) somewhat lessens the DVD-RAM format's perceived advantage in the data integrity category, but not in the data retention or damage protection categories.
DVD-RAM has a larger presence in camcorders and set-top boxes than in computers, although the popularity of DVD-RAM in these devices can be explained by its being very easily written to and erased, which for example allows extensive in-camera editing.
The on-disc structure of DVD-RAM is closely related to hard disk
and floppy disk
technology, as it stores data in concentric
tracks. DVD-RAMs can be accessed just like a hard or floppy disk and usually without any special software. DVD-RWs and DVD+RWs, on the other hand, store data in one long spiral
track and require special packet reading/writing software to read and write data discs. Like magneto-optical (MO) technologies, DVD-RAM has numerous rectangles on the disc surface that define the boundaries of data sectors
. However, DVD-RAM is not MO but a phase change medium, similar to CD-RW, DVD-RW, or DVD+RW.
Since the Internationale Funkausstellung Berlin 2003 the specification is being marketed by the RAM Promotion Group (RAMPRG), built by Hitachi
, Toshiba
, Maxell
, LG Electronics
, Matsushita/Panasonic, Samsung
, Lite-On
and Teac
. The specification distinguishes between:
Physically smaller, 80 mm in diameter, DVD-RAM discs also exist with a capacity of 1.46 GB for a single-sided disc and 2.8 GB for a double-sided disk, but they are uncommon.
DVD-RAMs were originally solely sold in cartridge
s; recent DVD recorders can work with discs either with or without cartridge, and many devices do not support cartridges at all. Discs can be removed from cartridges for use with these drives.
Many operating systems like Mac OS
(Mac OS 8.6 up to Mac OS X
), Linux
and Microsoft Windows XP support DVD-RAM operation directly, while earlier versions of Windows require device drivers or the program InCD
.
Windows XP
Home and Professional can only write directly to FAT32
formatted DVD-RAM discs. For UDF
formatted discs, which are considered faster, a 3rd party UDF file system driver capable of writing or software such as InCD
or DLA
are required. Windows Vista
and later can natively access and write to both FAT32 and UDF formatted DVD-RAM discs using mastered burning
method or packet writing
. Even though it is possible to use any file system one likes, very few perform well on DVD-RAM. This is because some file systems frequently overwrite data on the disc and the table of contents is contained at the start of the disc.
Mac OS
up to 9.2 (Mac OS Classic) can read and write HFS
, HFS+
, FAT
, and UDF
formatted DVD-RAM discs directly. Mac OS X officially supports DVD-RAM formatting and writing operations.
Many DVD standalone players and recorders do not support DVD-RAM. However, within "RAMPRG" (the DVD-RAM Promotion Group) there are a number of well-known manufacturers of standalone players, recorders, and camcorders that do support DVD-RAM. Panasonic
, for instance, has a range of players and recorders which make full use of the advantages of DVD-RAM.
Some DVD players with hardware DVD-RAM capability are sold without DVD-RAM support. As a specific example, Dell
uses the TS-L632D drive manufactured by TSST
in some of its laptop computers without DVD-RAM capability. However it is possible, with some difficulty, to replace the firmware with a non-Dell version which supports DVD-RAM.
The newest DVD-RAM Specification, DVD-RAM2 (also called RAM2), is not compatible with DVD drives that do not specifically support reading DVD-RAM2 discs.
Some high end products such as IBM's P-series
frames require DVD-RAM instead of DVD-RW.
DVD Forum
The DVD Forum is an international organization composed of hardware, software, media and content companies that use and develop the DVD and formerly HD DVD formats...
, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
s as well as camcorder
Camcorder
A camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage...
s and personal video recorders since 1998.
Design
DVD-RAM is one of three competing technologies for rewritable DVDDVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
s. Its competitors are DVD-RW
DVD-RW
A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.The primary advantage of DVD-RW over...
and DVD+RW
DVD+RW
DVD+RW is a physical format for rewritable DVDs and can hold up to 4.7 GB. DVD+RW was created by the DVD+RW Alliance, an industry consortium of drive and disc manufacturers...
. DVD-RAM technology provides excellent data integrity, data retention and damage protection through a number of mechanisms and properties. Therefore, DVD-RAM is perceived by some people to be better than the other DVD technologies for traditional computer usage tasks such as general data storage, and especially data backup and archival. The Mount Rainier Format
Mount Rainier (packet writing)
Mount Rainier is a format for writable optical discs which provides the packet writing and defect management. Its goal is the replacement of the floppy disk...
standard and SecurDisc for DVD+/-RW (which also works on DVD-RAM, CD-R, and CD-RW) somewhat lessens the DVD-RAM format's perceived advantage in the data integrity category, but not in the data retention or damage protection categories.
DVD-RAM has a larger presence in camcorders and set-top boxes than in computers, although the popularity of DVD-RAM in these devices can be explained by its being very easily written to and erased, which for example allows extensive in-camera editing.
The on-disc structure of DVD-RAM is closely related to hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
and floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
technology, as it stores data in concentric
Concentric
Concentric objects share the same center, axis or origin with one inside the other. Circles, tubes, cylindrical shafts, disks, and spheres may be concentric to one another...
tracks. DVD-RAMs can be accessed just like a hard or floppy disk and usually without any special software. DVD-RWs and DVD+RWs, on the other hand, store data in one long spiral
Spiral
In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point.-Spiral or helix:...
track and require special packet reading/writing software to read and write data discs. Like magneto-optical (MO) technologies, DVD-RAM has numerous rectangles on the disc surface that define the boundaries of data sectors
Hard sectoring
Hard sectoring in a magnetic or optical data storage device is a form of sectoring which uses a physical mark or hole in the recording medium to reference sector locations....
. However, DVD-RAM is not MO but a phase change medium, similar to CD-RW, DVD-RW, or DVD+RW.
Cartridge types
| Size | Bare disc | Non-removable cartridge | Removable cartridge | Empty cartridge/no disc | ||||
|---|---|---|---|---|---|---|---|---|
| sides | single | double | single | double | single | double | single | double |
| 12 cm | yes (type 0) | none | type 1 | type 1 | type 2 | type 4 | type 3 | type 5 |
| 8 cm | yes (type 0) | none | none | none | type 7 | type 6 | type 9 | type 8 |
Specification
Hitachi, Ltd.
is a Japanese multinational conglomerate headquartered in Marunouchi 1-chome, Chiyoda, Tokyo, Japan. The company is the parent of the Hitachi Group as part of the larger DKB Group companies...
, Toshiba
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
, Maxell
Maxell
, commonly known as Maxell, is a Japanese company which manufactures consumer electronics. The company's notable products are batteries -- the company's name is a contraction of "maximum capacity dry cell" -- and recording media, including audio cassettes and blank VHS tapes, and recordable optical...
, LG Electronics
LG Electronics
LG Electronics is a global electronics and telecommunications company headquartered in Yeouido, Seoul, South Korea. The company operates its business through five divisions: mobile communications, home entertainment, home appliance, air conditioning and business solution...
, Matsushita/Panasonic, Samsung
Samsung
The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...
, Lite-On
Lite-On
Lite-On is a conglomerate of individual companies that primarily manufacture consumer electronics, including LEDs, semiconductors, computer chassis, monitors, motherboards, DVD & CD devices, and other electronic components...
and Teac
Teac
TEAC Corporation is an electronics company based in Japan. TEAC was founded in 1953 as the Tokyo Electro Acoustic Company. TEAC has four divisions:*TASCAM - consumer to professional audio products, mostly recording...
. The specification distinguishes between:
- DVD-RAM version 1.0, recording speed 1x
- * Single-sided, one layer discs with a capacity of 2.58 GB
- * Double-sided one layer discs with a capacity of 5.16 GB
- DVD-RAM version 2.0, recording speed 2x
- * Single-sided, one layer discs with a capacity of 4.7 GB
- * Double-sided one layer discs with a capacity of 9.4 GB
- DVD-RAM version 2.1/Revision 1.0, recording speed 3x
- DVD-RAM version 2.2/Revision 2.0, recording speed 5x
- DVD-RAM version 2.3/Revision 3.0, recording speed 6x max
- DVD-RAM version 2.4/Revision 4.0, recording speed 8x max
- DVD-RAM version 2.5/Revision 5.0, recording speed 12x max
- DVD-RAM version 2.6/Revision 6.0, recording speed 16x max
Physically smaller, 80 mm in diameter, DVD-RAM discs also exist with a capacity of 1.46 GB for a single-sided disc and 2.8 GB for a double-sided disk, but they are uncommon.
DVD-RAMs were originally solely sold in cartridge
Caddy (hardware)
In computer hardware, a caddy refers to a sheath used to hold some media.If the medium is a hard disk drive, the caddy is also referred to as a disk enclosure, which is discussed there...
s; recent DVD recorders can work with discs either with or without cartridge, and many devices do not support cartridges at all. Discs can be removed from cartridges for use with these drives.
Compatibility
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
(Mac OS 8.6 up to Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
), Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
and Microsoft Windows XP support DVD-RAM operation directly, while earlier versions of Windows require device drivers or the program InCD
InCD
InCD is a packet writing software developed by Nero AG for Microsoft Windows.InCD allows optical discs to be used in a similar manner to a floppy disk...
.
Windows XP
Windows XP
Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
Home and Professional can only write directly to FAT32
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
formatted DVD-RAM discs. For UDF
Universal Disk Format
Universal Disk Format is an implementation of the specification known as ISO/IEC 13346 and ECMA-167 and is an open vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660...
formatted discs, which are considered faster, a 3rd party UDF file system driver capable of writing or software such as InCD
InCD
InCD is a packet writing software developed by Nero AG for Microsoft Windows.InCD allows optical discs to be used in a similar manner to a floppy disk...
or DLA
Drive Letter Access
Drive Letter Access is a commercial packet writing application for the Microsoft Windows operating system that allows optical disc data storage devices to be used in a manner similar to floppy disks. DLA is a packet writing technology for CD and DVD media that uses the UDF file system.Roxio Burn...
are required. Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
and later can natively access and write to both FAT32 and UDF formatted DVD-RAM discs using mastered burning
Image Mastering API
The Image Mastering Application Programming Interface, or IMAPI, is a component of Microsoft Windows operating system used for CD and DVD authoring and recording....
method or packet writing
Live File System
Live File System is the term Microsoft uses to describe the packet writing method of creating discs in Windows Vista and later, which allows files to be added incrementally to the media...
. Even though it is possible to use any file system one likes, very few perform well on DVD-RAM. This is because some file systems frequently overwrite data on the disc and the table of contents is contained at the start of the disc.
Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
up to 9.2 (Mac OS Classic) can read and write HFS
Hierarchical File System
Hierarchical File System is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs...
, HFS+
HFS Plus
HFS Plus or HFS+ is a file system developed by Apple Inc. to replace their Hierarchical File System as the primary file system used in Macintosh computers . It is also one of the formats used by the iPod digital music player...
, FAT
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
, and UDF
Universal Disk Format
Universal Disk Format is an implementation of the specification known as ISO/IEC 13346 and ECMA-167 and is an open vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660...
formatted DVD-RAM discs directly. Mac OS X officially supports DVD-RAM formatting and writing operations.
Many DVD standalone players and recorders do not support DVD-RAM. However, within "RAMPRG" (the DVD-RAM Promotion Group) there are a number of well-known manufacturers of standalone players, recorders, and camcorders that do support DVD-RAM. Panasonic
Panasonic
Panasonic is an international brand name for Japanese electric products manufacturer Panasonic Corporation, which was formerly known as Matsushita Electric Industrial Co., Ltd...
, for instance, has a range of players and recorders which make full use of the advantages of DVD-RAM.
Some DVD players with hardware DVD-RAM capability are sold without DVD-RAM support. As a specific example, Dell
Dell
Dell, Inc. is an American multinational information technology corporation based in 1 Dell Way, Round Rock, Texas, United States, that develops, sells and supports computers and related products and services. Bearing the name of its founder, Michael Dell, the company is one of the largest...
uses the TS-L632D drive manufactured by TSST
Toshiba Samsung Storage Technology Corporation
Toshiba Samsung Storage Technology Corporation is an international joint venture company of Toshiba and Samsung Electronics . Toshiba owns 51% of its stock, while Samsung owns the remaining 49%. The company specialises in optical disc drive manufacturing...
in some of its laptop computers without DVD-RAM capability. However it is possible, with some difficulty, to replace the firmware with a non-Dell version which supports DVD-RAM.
The newest DVD-RAM Specification, DVD-RAM2 (also called RAM2), is not compatible with DVD drives that do not specifically support reading DVD-RAM2 discs.
Some high end products such as IBM's P-series
IBM System p
The System p, formerly known as RS/6000, was IBM's RISC/UNIX-based server and workstation product line.In April 2008, IBM announced a rebranding of the System p and its unification with the System i platform. The resulting product line is called IBM Power Systems.-History:It was originally a line...
frames require DVD-RAM instead of DVD-RW.
Advantages
- Long life — without physical damage, data is retained for an estimated 30 years. For this reason, it is used for archival storage of data.
- Can be rewritten over 100,000 times for the lowest write speed discs (DVD±RW can be rewritten approx. 1,000 times). Faster DVD-RAMs support fewer rewrites (3x speed: 100,000, 5x speed: 10,000) , but still more than DVD+RWDVD+RWDVD+RW is a physical format for rewritable DVDs and can hold up to 4.7 GB. DVD+RW was created by the DVD+RW Alliance, an industry consortium of drive and disc manufacturers...
or DVD-RWDVD-RWA DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.The primary advantage of DVD-RW over...
. (These are theoretical numbers. In practice they could be smaller depending on the drive, the treatment of the disc and the file system.) - Reliable writing of discs. Verification done in hardware by the drive, so post-write verification by software is unnecessary. Software verification is disabled in all current DVD Video Recorders.
- Disc defect management designed to safeguard data.
- DVD-burning software may not be required — discs can be used and accessed like a removable hard diskHard diskA hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
. Mac OSMac OSMac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
(8.6 or later) supports DVD-RAM directly. Windows XPWindows XPWindows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
supports DVD-RAM directly for FAT32-formatted discs only. Windows VistaWindows VistaWindows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
is able to write directly to both FAT32- and UDF-formatted DVD-RAM discs from within Windows Explorer. Device drivers or other software are needed for earlier versions of Windows. - Very fast access of small files on the disc.
- Small 2 KB disc block size wastes less space when writing small files.
- Finalization not necessary. This is an attribute of the VR recording modeVR modeVR mode or Video Recording mode is a feature on stand-alone consumer and computer DVD recorders that allows video recording and editing on a DVD rewritable disc.In VR mode, users can create and rename titles for the scenes...
and is available on other media such as DVD-RW. - Media available with or without protective cartridges; can be used in the cartridge by many devices.
- In some video recorders DVD-RAM can be written to and read at the same time, allowing one program to be recorded and a different one, or an earlier part of the same one (time slip recording), to be viewed at the same time. This is an attribute of the VR recording mode and is possible, although only at lower bit rates, on other media such as DVD+RW.
- Supported by some high-end security digital video recorders, such as the Tecton Darlex, as a secure and long-lasting export medium.
- Holds more data when using Double Sided discs than dual-layer DVD+RW and DVD-RW - 9.4GB for DVD-RAM vs 8.5GB for DVD+RW DL and DVD-RW DL.
- Has write-protect tabs to prevent accidental deletion when used in a cartridge.
Disadvantages
- Media unavailability: Lower popularity of the format makes blank media harder to find at stores.
- High-speed media unavailability: 12x media is not available in the USA, nor Europe, even though 12x drives are readily available, and 16x media may not be available anywhere except manufacturers' R&D laboratories.
- Higher media cost.
- A hazard exists with 16x RAM2 discs in non-RAM2 drives: the disc may be ejected while spinning. Either way it is not a problem of DVD-RAM media, but the drives that do not recognize them properly.
- Less compatibility than DVD+RW and DVD-RW, despite predating both formats (as noted above).