Optical media maintains growth path
Speeds and interchangeability continue to be key issues as optical vendors move toward new formats.
Before the introduction of the CD, it would have been hard to state that optical storage had taken the mass storage industry by storm. Conflicting MO formats were the rule, rather than the exception...a situation that foreshadowed the turbulence regarding DVD formats. Purchases were delayed as the IT community waited out the survivors of the conflict. But with the staggering success of the CD, and the undeniable popularity of CD-R, it is possible to identify optical technology as a storage strategy that will not go away.
Equally important is the media itself. In examining the current state of optical media, reliability, interchangeability, and capacity share the spotlight as users seek insight into optical storage`s future. InfoStor recently queried optical media manufacturers to respond to current issues. Participating in the discussion were:
- Mike McCorkle, national technical support manager, Fujifilm
- Rusty Rosenberger, program manager, advanced optical technologies, Imation
- Rich Gadomski, national marketing manager, Maxell
- Hideaki Ohba, manager of technical strategic department, Ricoh
- Chris Smith, business development manager, Sony
- Tim Clatterbuck, director of marketing, Verbatim
FERELLI: Has the Universal Data Format solved all the problems of data interchange in CD technology? If not, what remains to be done?
SMITH: Not necessarily all of the problems, but most are now behind us due to this development effort by the Optical Storage Trade Association [OSTA]. Depending on users` CD-ROM or DVD-ROM firmware levels, a written CD-R or CD-RW disc may or may not be readable. Users have to make sure their ROM drives support UDF native, and if not, they need to support them with device driver software that interprets UDF format data on the host side.
GADOMSKI: It seems that compatibility problems persist from recorder to reader. This may have something to do with the various optical pickup devices and laser powers being employed.
FERELLI: Have rotational speeds reached their limits for reliable recording and playback?
McCORKLE: No. We think that rotational speeds can be increased in the future with laser power improvements.
SMITH: We haven`t hit the limits yet. For example, while 4X CD-R recorders are the mainstream, some vendors are shipping 8X CD-R drives with 16X in the R&D stage. With respect to CD-RW, the current market standard is 4X record speed, and systems supporting 8X and 12X are under development. As a result of competition, drive introductions are occurring at a pace exceeding Orange Book specifications. This can lead to potential compatibility issues when the industry adopts the next higher recording speed as a standard. There is some caution to be given when adopting high-speed CD-R recording because it precedes full industry testing and may ultimately lead to compatibility issues.
GADOMSKI: At higher speeds, achieving reliable recording and playback becomes more of a challenge. At some point, a balance between satisfactory speed and reliability must be achieved.
OHBA: Higher-speed recording standards are now under discussion. In one or two years, we will reach over 10X writing speed for both CD-R and CD-RW. For reading, we can reach the speed of a CD-ROM player.
CLATTERBUCK: There is always a danger when you`re pushing information from the system at higher speeds. The faster data comes across, the greater the opportunity for recording errors. It`s a challenge for drive and media manufacturers to reliably capture and store data at higher speeds. We`re dealing with the laws of physics, and at some point we`ll have to reach a level of diminishing returns. However, incremental improvements are still possible.
FERELLI: Which dyes assure the best reliability and longest archival life? What formulations are on the horizon?
McCORKLE: Today, there are three dyes: azo, cyanine, and phthalocyanine. These dyes can achieve over 100 years archival life. So, basically, there is no need to change these dyes from an archival viewpoint.
SMITH: All of the dye formulations exhibit adequate reliability. Formulation research is concentrating on higher-speed recording properties more than archival stability.
GADOMSKI: At this point, compatibility is probably more critical than archival life. Typically, cyanine is more compatible with various devices. Phthalocyanine is reputed to provide longer archival life. The question is, Does anyone really need 100 years of archival life?
FERELLI: A good question, but is any dye superior to another?
OHBA: In general, phthalocyanine dye is tough for light exposure or high temperature and humidity, compared to cyanine dye media.
CLATTERBUCK: Our testing has shown that metalized azo is far more stable than cyanine and phthalocyanine compounds. The metalized azo layer gives the disc a deep blue appearance, which is easily distinguished from the greens of cyanine and golds of phthalocyanine. But that is only part of the solution. Another part is the use of two layers to protect the reflective layer. The protective layer provides increased resistance to scratching. Our accelerated aging tests have shown that we can provide media that is highly durable over a wide range of temperatures, relative humidity, and time.
FERELLI: What is the future for capacities in the various forms of optical storage?
SMITH: Let`s start with MO. We are now developing the fifth-generation 5.25-inch MO drive and media, with more than 9GB per cartridge. This will be achieved primarily through the use of land-and-groove recording in conjunction with MSR magnetic super resolution technologies. Sixth-generation 5.25-inch MO is under consideration and the use of blue lasers, for example, can continue to yield higher capacities.
In the 120mm form factor, the two rewritable DVD technologies are the DVD Forum`s DVD-RAM at 2.6GB per side and the 3GB-per-side DVD+RW format. DVD-RAM has been commercially available since 1998, and DVD+RW will be available soon. Both products promise to deliver 4.7GB in the near future.
It`s clear that the market will not support all the rewritable DVD formats, and the race is on to see which ones will be supported by read-only (ROM) drives, because it`s the readability of written media in ROM drives that makes this form factor so attractive.
CLATTERBUCK: In the CD arena, 650MB media seems to be the ultimate capacity standard and is adequate for 90% of the applications. We are just on the front edge of the DVD technology curve. We have 4.7GB write-once solutions and have just announced 3GB rewritable capacities. We will be able to increase those capacities quickly while maintaining backward compatibility.
We need to provide an orderly and planned capacity growth path, but at the same time we have to maintain backward compatibility so customers can protect their earlier storage investments.
ROSENBERGER: In general, there are two different categories of optical storage media: prerecorded (stamped) and recordable (write-once and rewritable). In discussing recordable media, MO technology is also a factor, as it offers advantages in recording rates, cyclability, and areal density. The MO industry has developed techniques such as MSR, MAMMOS, and crescent recording (overlapping marks to increase linear density). Approximately a 2x increase in density can be achieved using these techniques, with capacities expected to reach up to 20GB per disk.
FERELLI: Where do you stand on NFR technology?
ROSENBERGER: NFR is being developed as a way for the drive to reduce the spot size by a factor of n (index of refraction of the lens), potentially increasing the data density by another factor of n2, which could be 4x to 9x for n = 2 to 3.
To preserve this spot size in the media, a flying head must be used, placing the lens within a fraction of a wavelength of the media surface. It has been estimated that capacities in excess of 200GB per square inch could be achieved by using all these technology advances combined.
For all forms of optical products, further advances in optics, high-powered laser diodes (going to 410nm blue laser), and media substrates will be needed to meet future storage requirements.
SMITH: NFR will yield tremendous capacity increases in the years to come. The market expects that certain companies will introduce NFR products by the year 2000. The questions we have surround the issue of data reliability, traditionally a key strength of MO technology.
You have to consider the issues involved with closely flying MO components and removable, contamination-prone media. After products are launched, we believe it will require several years of reliable operation of mass-produced NFR products before large-scale commercial data centers can safely adopt this technology.
FERELLI: Will CD technology be supplemented or replaced by DVD, once format issues are resolved? Why?
GADOMSKI: CD technology has a firm foothold in the market and won`t be replaced by DVD, just as the floppy has yet to be replaced by any technology.
McCORKLE: From a capacity viewpoint, CD will be replaced by DVD. However, CD-R/RW will continue to be a factor in the market because it is less expensive than DVD alternatives.
ROSENBERGER: Today`s ongoing format issues create confusion and fear of incompatibility in the minds of users. We believe DVD will ultimately replace the CD format simply due to the continued explosion of high-quality entertainment content, as well as the push from the content providers.
Large financial, medical and legal databases, motion pictures with tremendous special effects, and games with high-quality graphics all require more storage than is available from today`s CD technology.
Other factors that will drive the transition include the cost-savings in replication and distribution of video content, and the degree of copyright protection offered in DVD, which is not available in CD technology.
OHBA: CD products will survive a long time beyond 2000. DVD writable products need to establish infrastructure. They need more lead time to be widely accepted.
CLATTERBUCK: CD technology is firmly entrenched in the business, government and individual user market. We are now seeing CD-RW drives being designed into notebook computers and even low-end systems are adding rewritable CD solutions.
The media is as ubiquitous as floppies were 5 to 10 years ago. There are more than 150 million CD drives in use today and that volume continues to grow. We are having a difficult time keeping up with the demand for CD-R media, and we will probably experience similar demands/shortages in the CD-RW area later this year as people begin using rewritable CDs for more work-in-progress and temporary/long-term storage applications.
We aren`t even close to exceeding the capacity capabilities of CD technology today. According to IDC and other research firms the average data file is still under 50MB, and users can store a lot of 50MB files on a single disc.
I would imagine that even in 2005 people will be forecasting the demise of CDs, and instead of millions of discs we`ll be producing billions of discs. We are still a long way from saturating the market.
Mark Ferelli is editor-at-large for InfoStor.