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Seeing The Light

From STORAGE Magazine Vol 4 No 01 - Febuary 2004

Optical storage developments mean that magneto-optical disks and CD/DVD are seeing their replacements. Plasmon's UDO and Sony's PDfD have arrived. Holographic storage may be waiting in the wings.

Magnetics and optics have formed the mainstay of the serious archiving market for several years. Such magneto-optical (MO) disks have a 30-year life or longer and are recognised by authorities as suitable for archiving material. Plasmon is the leading UK supplier. Sony and Fujitsu are Japanese suppliers. The format is 5.25inch, holds up to 9.1GB, and requires a laser to heat a spot on the disk so that its magnetic polarity can be altered. Early disks required multiple sequential passes over the spot to complete this process but later ones concatenated the passes and so speeded up writing.

Convenience improved again when Fujitsu introduced a USB-powered 3.5inch 640MB MO drive in late 2002. Nevertheless MO disks started reaching the practical capacity limits of their format. The volume of material to be archived has grown, especially with the focus on data compliance regulations. What was to replace them?

The CD with its 640MB and cheapness has become an easy and practical way to backup up small systems, to exchange software and data and to provide simple and easy archiving. CD jukeboxes made it more practical but the CD has an inherent capacity limitation. Enter the DVD. Enter also standards chaos.

The DVD holds more than the CD, at 5.2GB, and as it goes through its double-sided and then twin-layer generations it will quadruple this. There are DVD jukeboxes available for archiving purposes, but the format is bedevilled by competing standards for DVD data writing. Suppliers have pursued the potential income stream from a market dominating format, competed at the format level and seen the overall DVD writing market diminished through their inability to work together.

A new higher-density Blu-Ray laser-based optical format has been pioneered by Panasonic. It uses a smaller diameter laser beam, thereby enabling smaller data bits and higher capacities. Panasonic has licensed the technology to other suppliers who, in a reprise of the DVD format debacle, are busy creating incompatible devices. There is a split between consumer Blu-Ray devices and data devices. No doubt consumer Blu-Ray devices will be used for data recording as they become available, but for now there are only two archive-class Blu-Ray formats: Plasmon's UDO and Sony's PDfD.

UDO
UDO features the new blue laser recording rather than the red lasers used in previous optical drives such as MO and DVD. First generation UDO products will have a capacity of 30GB, with capacity reaching 120GB by the third generation. Drive and media capacity are scheduled to double every 18 to 24 months. The densities achieved through blue lasers allow UDO to be priced at $2.00/GB in the first generation, one-fifth the price of MO media. It is available both in write-once and re-writable versions.

Hamish MacArthur, the head of research consultancy MacArthur Stroud, says, "Plasmon, a UK company with close associations with Panasonic, has introduced a format based on Blu-Ray technology known as Ultra Density Optical. The initial disk capacity is 30 GB with a potential growth path to perhaps as much as 320 GB. Data transfer rates are around 4.5 MB/s. Dell and HP are supporting the product. UDO uses a 5.25 inch disk in a caddy. It is exactly compatible with Magneto Optical disk cartridges and UDO will read MO devices. Plasmon's considerable heritage in the use of optical disk for archiving gives this technology a clear path at introduction."

"UDO is extremely cost-competitive in terms of initial purchase price, and on-going maintenance and operating costs," said Nigel Street, Chief Executive of Plasmon. "It is as low as one-sixth the cost of comparable disk solutions and approaches the cost of DVD library solutions with much greater reliability and performance."

Initial shipments of UDO products have already commenced and the technology has broad support from OEMs, including Hewlett Packard and IBM, ISVs, system integrators and other partners. "UDO is an outstanding technology advance in professional optical storage," said John Reed, Director of iSeries Product Management, IBM. "We are delighted to team with Plasmon and intend to support attachment of Plasmon libraries with UDO drives on IBM eServer iSeries servers."
By making UDO backwards-compatible with MO disks - it's still in a 5.25 inch format - Plasmon has provided an upgrade path to existing users.

UDO uses dyes on the disk which are phase-changed so that light is reflected differently. Plasmon says a UDO disk's life is over fifty years. Plasmon has introduced optical libraries supporting it, the G-Series. They were introduced at prices equivalent to those of existing MO (Magneto Optical) storage libraries, with triple the capacity, again providing an upgrade path. This is enhanced because there is support for both 30GB UDO and 9.1GB Magneto Optical media, reducing the need for media migration. There are entry level and mid-range configurations, with Plasmon aiming to make permanent archiving affordable for workgroup and distributed computing environments.

G-Series libraries include state-of-the-art features such as dual pickers, hot-swappable drives and redundant power supplies. They provide excellent access times, typically about 10 seconds, are designed for minimum downtime and are available in a broad range of configurations to fit differing requirements. Models range from 24 to 638 slots, with fully populated UDO capacities from 720GB to almost 20TB.

There is a second source for UDO media, however Plasmon is the only drive and library manufacturer.

PDfD
Sony has also introduced a Blu-Ray laser professional data storage product, called the Professional Disk for Data (PDfD). Ironically Sony was involved with HP and Plasmon in the original UDO specification-setting exercise.

PDfD offers 23GB (gigabyte) capacity on a single-side disc and is positioned, Sony says, as the natural successor to the 5.25 inch MO format, starting a forward-looking roadmap with capacities set to double every two years. However, Sony's PDfD does not offer MO-compatibility. PDfD media does offer competitive costs per GB and is available in rewritable and write-once (WORM) formats.

"Our Professional Disc for Data drives and media provide the ideal solution for storage users who have outgrown the 9.1GB per disc MO capacity, or for those who are looking for a more professional, higher capacity alternative to recordable DVDs", said Norio Yoshioka, Product Marketing Manager in Sony Business Europe's Storage Solutions division. Yoshioka continued, "The new format might even replace tape in applications where fast access and restore of archived data is key and users appreciate the convenience of removable optical storage."

This is perhaps a tad optimistic. Tape manufacturers, including Sony, are introducing WORM tapes and even disk arrays can now have a quasi-WORM status through software checks on the original unaltered data. However, for what we might call 'serious archiving', optical storage has the most momentum.

The Professional Disc for Data format provides more than 5 times the capacity of the latest 5.25-inch MO generation or any recordable DVD format. This is achieved by using a 405nm laser with a numeric aperture (NA) of 0.85 allowing a minimum mark length of just 0.16µm and a track pitch of 0.32µm, which is approximately half of that of the 9.1GB MO.

An air-tight drive design and an optical head with automatic lens cleaning as well as the dust-safe, robust and antistatic cartridge shell ensures that professional use reliability criteria are met. Regarding industry support Sony says that typical jukebox manufacturers such as ASM, DSM, SER and DISC/NSM as well as OEM customers such as LaCie and New ATG have been evaluating the drives and plan to offer their own products based on PDfD.

MacArthur's view on UDO and PDfD is that, "Sony's PDfD uses a more demanding lens design than Plasmon (0.85 numerical aperture compared to 0.7). The initial capacity is lower at 27 GB but the data transfer rate is 9 MB/s. The technical demands of the 0.85 NA approach may be one reason why the Sony product is later to market than Plasmon's."

"Both devices use high NA lens compared to CD technology at 0.5. This means that it is not possible to focus through a thick protective layer onto a recording surface. The protective layer is a lot thinner. The high NA also leads to a shallow depth of focus, increasing demands on the tracking system and the potential for errors. As a result, the disks are being protected from environmental degradation in caddies."

"Magneto Optical technology is not well placed to respond to these drives and retain compatibility with earlier generations. UDO offers MO drive users an upgrade path. UDO and PDfD offer the potential for optical disk to maintain its price/performance improvement of the last decade, continuing to outpace magnetic tape for mid range applications."

Holography
A third technology is still a future prospect. It is holography and is being pioneered by InPhase Technologies. It was founded in December 2000 as a Lucent Technologies venture, spun out of Bell Labs research, with the objective of becoming the first company to bring holographic data storage technology to market.

The company states that holographic data storage has evolved from several generations of optical recording systems, including the CD and the DVD. It is an optical technology that allows 1 million bits of data to be written or read in a single flash of light. Thousands of holograms can be stored in the same location throughout the entire depth of the medium.

Unlike other technologies that record one data bit at a time, holography allows a million bits of data to be written and read in parallel with a single flash of light. This enables transfer rates significantly higher than current optical storage devices. Combining high storage densities, fast transfer rates, with durable, reliable, low cost media, make holography posibly poised to become a compelling choice for next-generation storage and content distribution needs.

In addition, the flexibility of the technology allows for the development of a wide variety of holographic storage products that range from hand-held devices for consumers to storage products for the enterprise. Imagine 2GB of data on a postage stamp, 20 GB on a credit card, or 200 GB on a disk.

There's the rub. With UDO forging ahead to a forecast 320GB disk and UDO capacity doubling every two years according to Sony, delivering 210GB by 2010, then InPhase needs to get its product delivered by, say, 2006 to have any serious advantage as an enterprise storage medium.

Of course, it is still very early days for holographic storage and any capacity points are highly speculative. With UDO we have IBM and HP support. With PDfD we have the Sony marketing machine. UDO has built-in MO-compatibility providing an immediate upgrade path for existing MO users. This should enable UDO to rapidly build a customer base using Plasmon's existing OEM partners and their channel of integrators and resellers.

Sony has to start from ground zero with UDO and build a channel, relatively-speaking, from scratch. With no MO-compatibility then the appeal to existing MO customers will be limited and Sony and its partners may be looking for new applications.

As for the non-professional archive market, the SOHO and smaller SME organisations, it's perhaps readily apparent that some variation of DVD will become the long term storage choice du jour. DVD writers will be cheap, DVDs will be cheap and the software will also be cheap and easy to use. Drag and drop convenience will rule as users see the light. ST